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PC Fan of the Future?
baptiste writes "While we marvel at the latest CPU release or new motherboard chipset, we still put the same old fans in the neon lit cases and then complain that it is too loud. Well, maybe someone has finally come up with the next generation PC fan. Y.S. Tech has announced a new fan which is driven at the blade tips by a magnetic motor in the housing. Without the motor in the middle they claim a 30% airflow improvement meaning, potenitally, you could get the same airflow of today's fans at a lower RPM meaning less noise. They also claim the fan tips result in the bulk of fan noise. In this design they are sort of enclosed, reducing noise further. There is also a PDF datasheet available."
What do y'all think about this? Looks pretty cool to me (but what do I know?). Anybody know where to pick one up?
It's about time! I have seen some fans that apple curved tips and other methods to reduce noise, but this sounds like something that could be even more useful.
It seems to me that these fans sould also be more reliable. You don't need the axis to be anywhere near as complicated, since all it's doing now is providing a center of rotation. The motor is less likely to burn out, and also runs at a lower speed, which is always a good thing when it comes to longevity of hardware.
± 29 dB
interesting, I thought submersables used this already to get internal waterflow. because they couldn't have long lasting waterproof motors within the pipes, they had a fan that was driven by the outer ring so they didn't have the actual motor and electrical perts exposed to the water, I remember that they said something about the pressure and salt water being corrosive and the normal pumping systems not working well.
I'm still trying to fing an article, but it might have been in an issue of popular mechanics.
) Human Kind Vs Human Creation
) It'd be interesting to see how many humans would survive to serve us.
Euck!
dominionrd.blogspot.com - Restaurants on
Whatever happened to those goofy-ass wavy fan things? I just spent a few minutes on Google looking for them, but I can't find 'em. But then, these tip-driven fans move more air, not less air, so they'll likely catch on a bit sooner.
Writers imply. Readers infer.
...some fans that apple curved tips...
I should have used the "preview" button before posting! Who knew?
(If you haven't figured that out yet, it's "apply" not "apple.")
± 29 dB
Check out their FAQ page for details about how to get a free sample fan for testing and reviewing. The only catch is that you must have a website, and presumably you are meant to post a review on your site.
"Your's for a mere $100 each!"
Am I the only one who didn't see a price tag on this little gem? I might spend as much as $1 more for this new fan design, but I wouldn't spend twice as much. From the lack of a price on their webpage, that's probably what it costs. Prices are usually not easily gotten when the manufacturer is worried that its outrageousness will steer you away from their product.
I've got rid of my 60mm Delta with an 80mm fan and have a system that's bearable. The major source of noise right now is my power supply's fan from PC Power & Cooling (Turbo-Cool 300 ATX). Has anyone replaced their power supply fan?
Neat idea. I like to have enough fan noise to know that it's working with out having to put my hand behind the PC. I would not want to use one to cool a hard drive though.
..and then post to the discussion, thereby undoing any prior moderation. =P
± 29 dB
This is why dual-fan HSF setups primarily dominated, especially back when slot CPUs were still popular: you didn't have that static area of air. Sure, you had a hell of a lot more airflow from two fans, but one can argue that a lot of the kinetic energy is lost when air from the two fans collide.
Either way, this is a great improvement for CPU fans. Bravo, Y.S. Tech, it looks like you're taking the crown back from Delta (which is just more RPM, albeit much more noisy, for better performance).
Magnets right next to the CPU, eh? This is a good idea?
"Your superior intellect is no match for our puny weapons!"
I used to think this was a bad idea, people always used to warn of such things. I used to see people stick refridgerator magnets on their metalic computer cases. These people always seemed to have computer problems. I don't know if it was the magnets or just the breed.
Are computers more tollerant these days of magnets and electrostatic discharges? Or have people forgotten about these types of problems? After all I guess bugs (insects) can still do damage to computers they just don't blow the vacuum tubes like they used to.
I'm really looking forward to getting hold of these.
And the people shall be oppressed, every one by another, and every one by his neighbour Isaiah 3:5
So with my blinkenlights all taped up, and my fan silent.. I just need a way to find out if my systems are still running.
This is a good time for a next generation cooling system, as AMD's hammer chip will almost definitely require advanced cooling techniques to operate at safe levels.
The ability to monopolize an industry is insignificant, next to the power of the source.
Comment removed based on user account deletion
A big part of this for me is being able to turn off the MP3's every so often and have enough silence to think! I'd rather have a 500mhz that can do all the development I can throw at it, than a 747 powered fan sitting on top of a Gigahertz!
Seems that some of these companies are catching on that it might be possible to have the best of both worlds. My hope is that consumers will follow along enough to bring the cost of production low enough that even I can afford them. :)
The more you know, the less you understand.
Just how large a fan could you make using this principle? The fan next to my bed makes way too much noise and summer is coming.
Wow... I'm suprised nobody has though of this before. The design looks quite simple and is better than a traditional fan, much more so than just its looks.
The website shows here some of the interesting effects of moving the motor to the outside. The most important implication is that airflow is inceased near the perpendicular axis to the fan, ie., more air blows in the center of the fan than the traditional design allows. This helps out in heatsink designs in that it allows more air to cool the inner parts of the sink and thus cool it closer to the cpu core itself. The efficiency of the heatsink is now improved without a major redesign.
In the near future, I'm sure this technology will migrate to large fans for the case and powersupply, where its reduced noise will be appreciated.
--- At my sig, unleash hell.
It seems like every once in a while someone comes up with a latest-greatest new heatsink design. I've seen weird platinum peacock feathers and those wavy metal strips from a while back. They all look kind of goofy, and when really put to the test, don't do too much better. Short of pipes nd pumps, big hunks of copper attached to really fast traditional fans are still the best thing going, and I don't think that's for lack of effort at finding new things.
Because this is an improvement on the *fan* and not the whole heatsink, I give it a little more credence, but I won't be that interested until I actually see some Tom's numbers on it.
And I really won't be interested in it until the pricetag falls below $100 for a fan. For that money you could water-cool, or just soundproof your case.
In Capitalist America, bank robs you!
Lets not forget the new nForce chipset based on DDR333 capible of up to 5.33GB/s. This is probably now the fastest chipset availible (soon to be) for socket A. This with the new GeForce 4 and the new Athlon XP should make for some interesting benchmarks.
Saying Java is nice because it works on all OS's is like saying that anal sex is nice because it works on all genders.
Since the motor is located on the outer edges of the fan, would this have any effect on the lifespan of the fan? How about dirt accumulation?
The main problems I have with my cooling fans are balance, and dirt. When a fan has been running for a long enough time, somehow its balance shifts, and makes horrible loud noises. My server box is located in my closet, on the floor, with plenty of dust getting sucked into the case. It eventually got so bad that it caused the power supply fan to stop moving...
If this new fan design can overcome or lessen these problems, then I'll buy them as soon as they are available!
but this could mean quiter cases... well of course... but i mean just get a nice used chip (maybe 800-900 mhz) and underclock it down to like 500 mhz... and THEN add this fan that could be awsome... well maybe the opposite of awsome... kinda quiet and undisturbing... i already underclock my proc now but i still have a little noise from the fan and thats on the computer in my bedroom that i like to use for downloading while i sleep... thanks technology...
unzip; strip; touch; finger; mount; fsck; more; yes; unmount; sleep
Who needs a fan when you can buy a new Imac from apple thats so quiet and flow-efficent ya dunt even need a stinking loud fan or a quiter one!! and u can run linux on these macs!
This postsoon to be modded down by humorless people......
The only new thing about this is that they're using a normal "blade" type fan instead of a radial one. Probably the magnets are out of the ordinary too.
I've been using a Silverado cooler for a month now and it's extremely quiet. Plus, it's a solid German piece of work that makes it obvious how they can build such good tanks. If you're looking for a tried and true quiet CPU fan that's winning awards left and right, this is the way to go.
The point is that airflow increases with rpm times the SQUARE of diameter, which means if you make the fan 2x as big, you can make it 4x slower. The original NeXT boxes used a big, slow-turning fan to keep noise down, and it was quite effective. PC's usually use 3 inch fans but with some case mods could probably be set up with 5 inch fans, which for the same airflow could quiet things down a lot.
Add to that a hard disk with a fluid bearing spindle motor (pdf) and you've got a rather civilized box on your desk. I'm using one of these drives now (Travelstar 30GN) and the difference between it and an old drive is wonderful. The quietness is like getting rid of a toothache.
Almost all Apples SILENT (Apple 2, Apple 3, Mac+, IIfx, iMac, Cube, iBook, Newton, etc.
That is almost the main engineering case design criteria and why so many fussy demanding people like artists, musicians, scientists (chemists, biologists) and even programmers continue to support apple products.
PeeCees are like load aircraft carriers or at least Vaccuum cleaners comapred to the majority of the most popular selling Apple Computers.
Did you know the Apple 2 had NO FAN at all?
Same with the Mac Plus... no FAN at all.
and most all the products since the IIfx have a variable speed fan that increases rotation only if truly needed... like the Wallstreet G3 laptops.
When Steve jobs created the NeXT workstation he designed every cable to be one long 10 foot single cable so that the machine (almost quiet) could be hidden insode a closet or put very far from your monitor! He hates noise of all kinds.
Hurray for quiet or semi-quiet hardware.
"...the torque of motor becomes even much more powerful than ever."
They advertise the torque as being much higher than other fans, but of course it is. They've sacrificed RPM, therefore airflow:
"...you should not only look at the airflow and static pressure to determine whether T.M.D. FAN is better or worse than traditional motor fan."
And a lot of the reasoning behind the idea of a heatsink, is that you don't need to have all of the air flow at one point. It's spread out.
There may be good economic reasons to put the motor parts on the OD of the fan and that is good. But, all statements about the air flow and cooling capabilities are pure PR.
First, the velocity of the blades near the hub are too slow to put work into the air and therefore the air tends to leak backwards near the hub. This is why putting the motor in the hub area does not degrade fan performance.
Second, while the fastest parts of the fan (the blade tips) make most of the fan noise, changing their shape does the most to reduce the noise. The noise has nothing to do with the "motor parts" that reside in the blade tips in this design.
Third, the pressure generated by the fan is solely dependant on the fan design and has nothing to do with how the fan is powered.
Fourth, of course the torque is more effective at a larger radius, but this has nothing to do with efficiency.
Fifth, any increase in air flow has to do with the shape of the blades and the speed of the fan and can probably be improved a somewhat by blocking the hub a little.
Sixth, I do not see how the fan improves the efficiency of cooling anything. Increased air flow will cool anything better, according to how much horsepower do you want to put into your fan. And, it matters a whole lot where the parts to be cooled are in relation to the exit air stream, etc.etc.etc. Nothing but PR here.
Most of the noise is the disk drive, at least in my PowerBook (400MHz).
Similarly for the iBook (now up to 600MHz), and there's a variable speed fan in the iMac (800MHz, but I suspect the lower 700MHz will run cooler).
Macs have been known for a while as quiet computers.
GPL Deconstructed
If you're looking for an amazing cooling product for your hot CPU, 3D card, etc., check out this page: zalmantech.com.
Now, if those products could be combined with the new fan technology from Y.S. Tech, we could have the next generation cooling solution at our fingertips. Zalman's cooling products really made my Athlon XP 1700+ a lot colder than with the default fan system, and made it virtually noiseless, as the fan runs at 1600 RPMs!
this fan has already had some discussion on the various case/cooling forums:
amdmb
ars
Having torn a many pcâ(TM)s apart, to the risk of slicing my hands upon the un de burred sheet metal. I have noticed 1 common elements that contribute to fan failure.
Too much heat on the oil seal
Looking at this compared to a ordinary fan, it looks as though the bearings and oil seals are evenly dispersed over the surface area of the heat sink, where most common fans have the bearings and oil seals right in the center in the middle of rising heat. Iâ(TM)m not a thermodynamics expert but I can tell you from experience that I have been able to bring many a dead CPU fans back from the dead simply by peeling the sticker off in the center and dropping a dab of oil in there.
Anyways thatâ(TM)s my 2cents
For years the huge cooling fans like those on board train locomotives have used a neat trick to keep the noise down. Instead of placing the fan blades at equal angles from each other, they are offset by a small amount. This actually results in a lot MORE noise but it's all outside the human hearing range. The same trick works for small fans as well but no one ever seems to take advantage of it. You basically hear nothing but the motor. (By the way. Does anyone know if there is a manufacturer of these in existence? My computer could definitely use a fan upgrade.)
"Who is General Failure and why is he reading my disk?"
This sounds very simmilar the the way a Technics turtable is driven. If it is I'm getting one just so I can say I have a "direct drive" fan!
not if he has 2 accounts...
I just replaced the whole Power Supply. You can't beat the Enermax Whisper series. Dead silent (12db), and runs like a dream.
It is, unfortunately, about US$40-50.
Wouldn't it just be easier/better to stick a plastic duct over the CPU, and put the fan a little bit away from it? That way there's no dead air space.
It doesn't mean much now, it's built for the future.
WOW! No fans at ALL? SHOCKING!
Not really, though. I'd like to see a mac that can outrun my machine. They may be quiet, but they just don't render fast enough.
How far from your hardrive should you keep it?
It seems like a nice way to run a fan as long as it's not flippin' bits in the process.
I think this is a brilliant product for all the reasons given by others but I would also like to say that I liked the web site. OK, the background etc. are naff but it had *real* information about the product instead of just a lot of marketing rubbish that tells you no real facts.
I hope we get to see these gizmos in our PCs soon at an affordable price.
I love stacking my barbecues in the shed at the end of summer - you can't beat a bit of grill on grill action.
The new iMac does have a fan, just a really quiet one. Quieter than the hard drive. And I'm not even sure that it runs all the time, because the airflow is pretty well straight up and out. Mostly, though it's quiet because PPCs don't generate as much heat as Intel chips, and don't need so much Raw Cooling Power.
it's not about the karma, it's about the whuffie
I emailed the manufacturers regarding the free tests. Here's what they said:
;) I wonder why?
Thank you very much for your high interests in Y.S. TECH's revolutionary new product: T.M.D. FAN (Tip-Magnetic Driving Fan).
After the announcement of the T.M.D. FAN, we have been receiving uncountable inquiries everyday to review the T.M.D. FAN, to obtain the T.M.D. FAN samples and to attain developing schedule. To deal with all of your inquiries and be fair to everyone, here is what Y.S. TECH would like you to follow. We appreciate for your cooperation in advance!
1. Please visit Y.S. TECH web site at http://www.ystech.com.tw to obtain the detailed information (including technical issues).
2. We hereby enclose some images (.jpg at 72 dpi) that you are very welcome to apply them to your web site's product review and news announcement.
3. After your post or announcement of the T.M.D. FAN in your web site, please inform us the links. Then we will deliver physical T.M.D. FAN samples (possibly with heatsink) for your test and review purpose. The samples will be delivered to you in the middle of April.
4. After your test on the T.M.D. FAN, you will be much appreciated, if you post the test results and comments in your web site. It doesn't matter the results or the comments are positive or negative. The general public needs the truth.
Here is the rough schedule for the dimensional development of the T.M.D.
FAN:
Now: 70x70x15mm is now available. It is targeted for Pentium 4 CPU cooler.
April: 70x70x15mm T.M.D. FAN will be shipped out to variable locations over the world.
May to June: 60x60x25mm, 80x80x25mm T.M. FAN will be released to the market. These two dimensions are targeted for AMD CPU cooler and case cooling.
Again, thank you very much for your interests in T.M.D. FAN!
Should you have any questions or comments, please feel free to contact us. Y.S. TECH will reply to you as soon as possible.
Note the "uncountable enquiries..
I think their attitude about the reviews is very good. It's a shame more companies aren't like that.
--
Andy
Another one of those "too cool to be
useful" cooling fans.
Center area has minimum effect on air
transportation. Outside region of blade
has most effect on air transportation.
Too sad that blade diamater is redudced
because "motor" sits outside.
Heat from chip goes into heat sink. Heat
sink has very good thermal conductivity
(Alumininum or copper, much better than
transition region heat sink -> air). So
think of heat sink as an ideally stirred
container. Weak additional middle air
flow doesn't improve cooling. Reduced
outside air flow _does_ reduce cooling
performance.
What makes an effective cooling device?
* High surface heat sink with good thermal conductivity.
* High volume, turbulent of air flow over whole surface.
* Fancy design does move your money but doesn't move heat.
I've replaced my PS fan with a silencer fan from PC Power and cooling. Take out the old fan and replace with new one. String power wire out of the PS with the other wires, and connect to power connector. It's very quiet (rated at 20 dba), and has the same airflow as a regular PS fan.
Check this site
There are some pictures aswell. Unfortunately most of the details are in Danish only, but the short story is that they offer a silent fan-less PC using a patented liquid cooling system, that doesn't use electricity.
This fan is powered by 4 motors at the corners. Since I'm no physics wizard, could anyone explain the consequences should any one of these motors fail. The obvious effect would be reliance on the motors that are left.
Will this off-balance the alignment of the fans? Is there a probability that this will then dislodge the fan, thus causing damage to other parts of the computer?
All opinions are very much appreciated.
Welley Corporation - SLM Scammers
(air, that is.)
Which makes them ideal for your WinXP box.
--
The Cap is nigh. Time to get a fresh new account.
http://www.overclockers.com.au/techstuff/a_tmd_fan /
> Did you know the Apple 2 had NO FAN at all?
Neither does the Tandy 1000 RL I've got sitting over here. So what? They're both old and slow, and neither has the processor power to justify a fan.
Which bring me to the conlcusion that a nice feature for /. would be to include [domain](pdf) after a link to indicate a pdf file. A similar thing is seen in Google search results. The page lengthener prevension thing is way cool. Brav, /.
WOW! No fans at ALL? SHOCKING!
Not really, though. I'd like to see a mac that can outrun my machine. They may be quiet, but they just don't render fast enough.
The iMacs (except for the new lamp one) and the cube are examples of modern Macs that don't have fans. They're considerably faster than the older fanless Macs.
have been around for a long time. a Squirrel cage fan is the quietest as is ducted fans and low rpm but high blade pitch fans. The problem is that these fans run off of 110 volts, and are expensive. (100.00 for a squirrel cage compared to the $6.00 pc case fan) Plus you have the ability to abate the noise easily by adding filters, rubber noise isolation mounts to seperate the fan from the case to reduce sound transmission.
A near silent pc is easy to do if you want to spend the money and get good at metal modification and engineering your own isolation mounts. I have a server that uses a squirrel cage blower on the back the intake is via a pair of filters and I produce a 4psi static pressure INSIDE the case with all the "stock" fans reversed to blow out instead of suck in dust.
Do not look at laser with remaining good eye.
The cube has 733 g4 processor I think.... its the case design that dissipates heat using columnar chimney effect that allows macs to avoid fans, or noisy fans..... its not just a factor of processor power... the cube is a year 2000-2001 unit.
Here are some html pages with specs, you can find them by going into the dir that tmd-0.htm is (has full dir listing, with lots of pics!), or just by clicking below, has lots of scientific shit with heat flow, etc...:
http://www.ystech.com.tw/Tmd/tmd-0.htm
http://www.ystech.com.tw/Tmd/tmd-1.htm
http://www.ystech.com.tw/Tmd/tmd-2.htm
http://www.ystech.com.tw/Tmd/tmd-3.htm
That was then...
Now the iMac, iBook and PowerBook all have fans. And Power Macs now have 3 fans!!!
So much for the silent office...
I agree with the previous comment:
1/ A fan generates nearly no flow at the hub so it
is not necessary to remove the motor
2/ Providing there is a bit of distance the air
vein _contracts_ behind the fan, hence reducing
the hub's footprint
3/ Most noise is generated at bearings and blade tip.
4/ Noise and cooling can be improved by improving
swirl and turbulence.
5/ Airflow behind such cooling fans is not axial
6/ Small blade chords mean low Reynolds numbers mean low efficiency
Did you know the Apple 2 had NO FAN at all?
Neither did the Commodore 64. What was the point there?
Someone set us up the bomb, so shine we are!
This fan would be much quieter and probably better than my Globalwin WBK38. 6800 RPM is really loud.
If you want an almost silent fan, check these out. Very cool.
So how's the crack today? You don't have to waste your modpoints to mod fr0st pi5t!s down, the resident censors with unlimited modpoints will do it for you.
Yeah, I know, first and second post = redundant, ha ha funny...
This fan seems to have both advantages and disadvantages. The most obvious for me advantage is that its axis vibrates less -- force is applied to the edges of the fan, straightening it. That may help with the problem that often kills "classic" fans -- the bearing (that usually is a brass pipe attached by one end to the plastic base and a steel pin attached by the opposite end to the hub of the blades) wears out unevenly, what causes the fan's pin to roll in the pipe, and with precession causing further damage that, among other things, converts a cylindrical surface into a cone, making a bad problem even worse, causing more noise, vibration, squeezing out the lubricant and clogging of the bearing.
;-).
Another positive thing is that this design (but not the device itself) allows for relatively easy improvement -- even though the picture looks like the bearing is the same as I have described above, this can be converted into a "reversed" bearing design without the motor getting in the way -- a pin can be attached to the plastic base/grille at both ends, and a pipe (or ball bearings, or whatever) -- to the middle of the hub. Then the fan will be also symmetric and even less vulnerable to the vibrations. "Classic" fan design can be converted into this, however then the rotating pipe would push back already tiny coils and cores of the motor. With coils outside, and reduced vibrations in the first place this would be more efficient (and oh, btw, if some asshole will try to patent this, I would be happy to see him in court, with this comment as an evidence of the prior art
The disadvantages are also obvious. First, blades, even with heavy magnet ring on their ends, are still flexible and prone to deformation. This may affect the balance of the rotor in the long run -- "classic" fan has a smaller ring magnet in a sturdy plastic cup of the hub, and therefore is almost invulnerable to this (until the bearing wears out enough to shift the center -- but by then the fan would be dead already). Second, this, and plain need to accommodate heat expansion, precision of manufacturing, etc. increases the necessary gap between magnets and cores. That would require larger, stronger coils, but there isn't that much space available for them in the corners.
Contrary to the popular belief, there indeed is no God.
I'm suprised the fan has a center bearing at all. If you used something like maglev train design to "levitate" the outer edge of the fan blades, then the whole fan could spin in free air. No bearings should be quieter and have a much longer service life.
Well, he does seem to like the sound of his own voice.
Ooooohhhh cheap shot.
I'm a PC fan, so does that mean I get to be plugged into the back of a computer?
Then again, I also used to like tractors, so does that make me an ex-tractor fan?
....sorry... I couldn't resist it....
(Spudley Strikes Again!)
Some of the best info that has been posted about the ways this fan *can* be effecient and quiet.
Kindness is the language which the deaf can hear and the blind can see. - Mark Twain
Why use electric fans? Everybody has to breathe, so put on a gas mask, connect it with a long straw that terminates at the CPU heatsink, and breathe really hard for extra cooling!
;-)
Maybe this way coders will write more efficient programs. If they don't - they'll hyperventilate, hmmmmm
A caveman dreams of being us, the incalculable power and riches. We dream of being Q, then what?
Fan of the future? Feh... where's the liquid nitrogen dammit?!
one thing I noticed that was really smart about a little dell optiplex we have is the fan.. it has a 3" squirlcage fan.. like you have in most home forced-air heating/ac systems.. or range hoods. it's very quiet, and moves a signifigant ammount of air.. like someone posted earlier.. the blades in the center move slowly, and the blades at the edge move fast, so you don't get an major advantage to having the motor on the outside. with a squirlcage fan, all the blades are on the outside, moving at the same speed. now just combind that with variable speed cooling.. and things will be very good.
The site is in Chinglish.
It is amazing that the Chinese never think to go to a local guest house for foreign backpack travelers (like the Amiga guest house in Taipei), and ask for help with their English.
I wrote a letter to the web master:
Daniel,
You need help with the English on your web site.
I suggest you find someone who speaks English well at the Amiga guest house in Taipei. There are many well-educated travelers who would work cheaply to help edit your English.
Also the main page has some coding problems. The menu should be at the top. The page size should not be limited, because with some monitors and resolutions, it is not possible to see the menu.
Michael
Bush's education improvements were
2) Pentium 4 at 0.13u is hotter than TBred
3) Pentium 4 operates much closer to its max temperature (70C) than Athlon XP (90C)
4) So Intel chips are the ones that will benefit from this new fan.
Hammer is not that much larger than Athlon, and it has a quick migration into the mobile arena, so I would hazard a guess that it does not run that hot at all.
AMD are showing off a TBred running at 2800+ speed at CeBit anyway, for all those naysayers that say that AMD can't perform. You have got it wrong every time in the last 3 years. "Athlon, yeah, right!", "Yeah, they won't get their 0.18u process working", "It won't scale in clock speeds", etc. I'm bloody tired of this anti-AMD FUD that is always being spread everywhere.
Basically, competition is good. Lets hope that in the desktop x86 market, AMD and Intel end up with 50% each - that will promote competition the best.
Maybe I'm missing something... I used these fans back in 1987. I don't remember the brand, but I remember a co-worker holding it out the car window while going down the freeway and getting magnet shrapnel in his hand when the outer magnets blew off the fan tips and exploded against the outer frame. These were power-supply size, not CPU size, but still... Simple idea, it's been done before.
Ditto on the Enermax. I just bought a 431W unit with a knob to manually control the fan speeds. While not the 12db whisper model, it is still very quiet... maybe 24db and has plenty of amperage for my heavily overclocked machine that has 6 disk drives in it.
Don't I recall lots if not all of those early computers having an external AC/DC converter, either as a wall wart or as a box midway up the power cable? IOW, your primary source of heat was moved AWAY from the computer case, and since 6502s really aren't known for their heat problems, of course you wouldn't need a fan. The PC has a switching power supply because it was far more expandible than anything else out there at the time, and the power requirements needed to be more flexible. This was not limited to the IBM - my TI-994/A's external expansion box (circa 1979) had a little power supply in it (don't recall if it had a fan, I think it did) because again, I could put a variety of peripherals in there, and it needed to be able to run them all.
Yet, my base TI-994/A ran off of a wall wart.
Recall that until around the 486 DX/2 days, there (in general application) wasn't anything hot enough inside the PC case to warrant its own fan. The fan behind the power supply is/was always meant to cool the *power supply* anyway.
I have a question to some air-flow engineer out there that I've always wondered about this issue.
Is it possible to use the temperature differential between the heat inside the case and the outside to create some passive cooling system? It seems like it should be possible to use the energy in the heat someway to move the air around.
Is there just not a good technique to do this, or is there some other problem that I'm not thinking of?
Sometimes it's best to just let stupid people be stupid.
When Steve jobs created the NeXT workstation he designed every cable to be one long 10 foot single cable so that the machine (almost quiet) could be
hidden insode a closet or put very far from your monitor! He hates noise of all kinds.
Maybe he designed it that way, but that's not the way any of mine are. My Mono ones have a short cable, and the Color ones make like even more fun with the sound box stuck in the middle of it all...
It is my understand that, although water is diamagnetic.. you need HUGE magnetic fields to manipulate it. You say that this is common in homebrew watercooling? I really can't see how. It would be neither efficient nor practical.. unless somehow you have a 5 tesla watercooled bitter magnet at home to move that water with..
Yes they don't need fans becuase they are all ridiculously slow compared to their pc counterparts!
Squirrel cage fans are even more expensive then you said. You forgot to factor in the cost of the squirrel and squirrel chow.
And forget about cleaning out the damn things. Most squirrels don't last more than a week.
Poor little bugger, being made to power a fan by application of 110 volt AC. It's inhumane I tell you.
144l. ph34r my 133t l3g4l 5k1lz!
Sorry - I just had to say it.
"No matter where you go, there you are." -- Buckaroo Banzai
I think all of those Apples he mentioned have an internal power supply..
With center-motor fans, after 3-4 months continuous usage the coils and bearings get clogged with dust/cigarette smoke/cat hair/etc.
:)
Eventually it slows the fan down, so all you need to do is blow the dust out with some compressed air, right? WRONG!
Every time I try to clean a case fan or cpu fan in this way it will fail completely within 5 days of cleaning. I don't know why, but at $15-20 a piece I just take the hit in the wallet and turn the other butt cheek
But, I suspect that with the motor on the outside, it won't be exposed to so much crap and might last a little longer.
An interesting side note: I finally got a motherboard that has cpu temp monitoring software and I've watched the temp gradually rise after a few months of use as the blades and motor collect all that crap I breathe on a daily basis!
A vacuum is a hell of a lot better than some of the stuff that nature replaces it with. - Tennessee Williams
Fans can be made without blades. Nikola Tesla invented bladeless turbines and pumps using a stack of smooth discs with inlet holes (for a pump) near the center of the disc. The fluid enters near the center and is pulled by the discs towars the periphery.
As a turbine, this would made an excellent substitution for a piston engine in a hybrid-electic vehicle!
http://www.execpc.com/~teba/main.html
*Don't do it!* I tried almost exactly the same thing - replacing the regular PC Power & Cooling Turbo Cool 350 power supply's fan with a Silencer fan - and got unacceptably high CPU and mobo temps (CPU up around 70 degrees C).
What *does* work (but costs money) is replacing the entire power supply with the Silencer 400 ATX power supply. That does have the Silencer fan, and the power supply has been engineered to give adequate cooling with the lower-speed fan. The Turbo-Cool power supply definitely hasn't. After spending the $$$, I'm poorer, but have a lovely, stable, *quiet* power supply and a nice cool CPU and mobo.
The further you have mass from the axis of rotation the more likely you are to have imbalances, vibes and noise. If these things have magenets on the tips, expect them to wear out their bearings fast and sing.
DMCA, Hollings, Palladium. What might have sounded like paranoia is now common sense.
It's interesting that nobody mentioned ducted fans. That's exactly what this is. Not only is a lot of noise created at the tips of fan blades, or propellors, there is an aeordynamic effect at the tips that causes a loss of effiecency (without going into a ton of detail). Putting fan blades inside a housing as such nullifies this effect. Notice also that they termed the fan blades as an "impeller"?
.....
All modern TurboFan engines are essetially the same thing except there is also a gas turbine engine at the core or center.
blah blah blah
He made more sense then you do. You: I thought of this concept a while back, even started modelling it in Simulink (part of Matlab).
Nice work, drawing pictures lends credibility. Nope. I'm a Mechanical Engineer. I've done some rudimentary fan designs (you know vector diagrams, work balance, that kind of thing), but I won't play a fan designer on TV or stomp reasonable people. Him: "First, the velocity of the blades near the hub are too slow to put work into the air and therefore the air tends to leak backwards near the hub. This is why putting the motor in the hub area does not degrade fan performance."
You: First of all, the hub is smaller, meaning the there is more air intake near the hub...anything which calls for a greater air debit at the top of the fan is good. The air will only 'leak back' if the air pressure under th fan is greater than on top, which doesn't happen until you hit high RPM's. What you will get is vortices under the fan near the hub, which is good...it means a lot of airflow over the die of the chip, which leads to cooling of the chip. Note that this happens under the fan, which is where you do want vortices.
He's right, again. If your fan does not give you any pressure increase, you have a poor difuser or a poor fan or both. There is zero motion at the axis. The best thing to do with that air is to redirect it outward towards your blades. If your hub does not do this, you might get some recirculation there that will do what your hub should have. Him again: "Second, while the fastest parts of the fan (the blade tips) make most of the fan noise, changing their shape does the most to reduce the noise. The noise has nothing to do with the "motor parts" that reside in the blade tips in this design."
You: The thing is, the tips of the blades are in the ring surrounding the fan...now the air first gets led through a bounding area before it gets spun by the fan...it goes from vertical to horizontal directly, like in any good pump, without having that airflow distorted by the boundary conditions created by the tips of the fan being near but not touching the side of the fan case. Vortices on top of the fan only make for a decrease in airintake which is bad for cooling.
Huh? What does that have to do with what he said about decreasing noise by changing blade shape? Any axial fan will create an axial vortex above it unless you put stator blades in the way. If you want to get rid of the blade tip vorticies you change their shape, or you could put a ring around them but that makes other problems. Him: "Third, the pressure generated by the fan is solely dependant on the fan design and has nothing to do with how the fan is powered."
You, again: But here the method of powering the fan has led to an improvement in fan design (more air intake due to higher area of the fanblades).
You are starting to repeat yourself, which would be OK if you were correct or even consistent. You know, he's right again. While you fail to actually contradict him, you do contradict yourself by not bothering to say anything about pressure differences that you don't understand very well. Him: "Fourth, of course the torque is more effective at a larger radius, but this has nothing to do with efficiency."
You: Thiuss hasd no bearing on the situation other than stating that the larger a fan is, the better it works...duh, we already knew that.
Ummm, that's not what he said, but it's nice to see that you have the spirit to be condesending. Can you explain why a larger fan works better for us? Is it because the ends may be turning faster? Isn't this why axial turbines are generally rows of blades mounted further away from the axis than they are long? Would they be more efficient with a large hole in the center? Him again: "Fifth, any increase in air flow has to do with the shape of the blades and the speed of the fan and can probably be improved a somewhat by blocking the hub a little."
You, sigh: No, that would only limit the area of air-intake, which is bad...you want a big area of intake, to get as much air down the fan as possible. Blocking the hub is a Bad Idea(tm)
Do you know any other tune than, "this thing rocks because it has a smaller hub"? I think I've alrady stated the purpose of the hub. Go figure. Him: "Sixth, I do not see how the fan improves the efficiency of cooling anything. Increased air flow will cool anything better, according to how much horsepower do you want to put into your fan. And, it matters a whole lot where the parts to be cooled are in relation to the exit air stream, etc.etc.etc."
You: Yeah, you got the idea...this new design improves airflow, which is good!
Same tune. You know what is good but not how to achieve it. He does. But wait, you have a conclusion: Not PR, just airflow...they increase the airintake (by having a smaller hub, which also means better cooling near the centre of the fan) while lowering vortices near the airintake (by having a seamless fancase-fan interface), thus creating better cooling
OK. Does anyone have any numbers around here? Like flow vrs current for various radiuses? Yes that would be useful, a repeatable experiment comparing various available designs. The data sheet is slashdotted. Perhaps you can CAD up some drawings of a test bench for us?
DMCA, Hollings, Palladium. What might have sounded like paranoia is now common sense.
If you don't like taking the hit, here is what you can do (if you don't mind taking the time):
Fan motors are really nothing more than funky four pole stepper motors, of a sort, with all the switching electronics built into a small board in the fan. They are true brushless motors (just like stepper motors). Coils are located on this board, and the fan rotor has a ring magnet which spins around the coils on a bearing (typically sleeve, but sometimes ball).
Now, the shaft is fixed to the fan blade rotor, and passes through the bearing, and out the backside of the drive electronics carrier board (the bearing is mounted to the carrier board). Look at the "backside" of the fan, where the wires enter the fan, and you will (or should) see a sticker, showing the make of the fan, rpm, etc. Remove this sticker, and there should be a hole where you can see a plastic or metal "lock ring" surround the shaft of the fan.
Remove the lock ring (don't lose it!) with a couple of small screwdrivers or a pair of tweezers (if you a real good, dremel the tips of the tweezers to make small hooks on the ends, forming a "puller") - the lock ring is typically only held on by friction (it doesn't need to be anything more, as the magnetic field of the rotor ring magnet keeps the fan aligned with the steel armature of the coils on the driver board).
You should now be able to remove the fan blades.
With the blades off, inspect them for dust and dirt around or one the shaft. Clean the blades with compressed air, maybe a qtip with some water - clean the shaft with rubbing alcohol.
Clean the circuit board and the fan cage with compressed air, and inspect the bearing. If it is a sleeve bearing, use a needle or other shaft size implement to drip some rubbing alcohol through, and disolve any old grease - if it is a ball bearing, you might try to do the same - if you can remove it, even better to clean it outside of the fan circuit board.
Once the shaft and bearing are dry, repack the shaft and the bearing. If the bearing is a simple sleeve bearing, apply some petroleum jelly to the shaft (just a little), and slide the shaft back on. If it is a ball bearing, apply the jelly to the bearing, putting some light pressure on it to force it into the bearing, and a little on the shaft, then reassemble.
Clean your hands thoroughly and dry them, then remount the locking ring. Clean the area around the hole (not in it!) with rubbing alcohol to remove any traces of oil, then place one of those "garage sale" round stickers over the hole to replace the original (and maybe mark the current/voltage ratings and cfm on it as well).
That's it! It takes a little time, but costs less than buying a new fan (especially if it is late at night or something and no place is open). Keep it under 15-30 minutes, and it is even worth your time, if you think that way. Most of the time, the reasons fans fail after using compressed air on them is that the dust and dirt either get blown into the bearing, or the fan is spun to an ultra-high speed past the bearing's rated speed, and the failure begins.
Hope this helps!
Reason is the Path to God - Anon
A couple of months ago I helped my brother-in-law replace a water-pump on a car - to get to the water pump you had to damn near take the entire front of the engine off. Anyhow, at the time, I looked at the radiater fan blade - and it was of an "asymetrical" alignment - five blades, but with some at strange angles.
I wonder if this was done to reduce noise...?
I've got someone else's Unix box near me, and it sounds like a 747 revving up. He moved into another room but left his beast behind :-(
I've got a couple of fans that look suspiciously like this that I'd bought ages ago for replacement fans for 486 fansinks. Nifty little fan, motor at the edges of the blades.
I am not merely a "consumer" or a "taxpayer". I am a Citizen of the State of Texas
Yeah, and overheating with no fan to mitigate it was probably why a friend's Mac caught on fire -- it literally had flames shooting out of the back -- which in turn set the curtain behind it on fire, and was working on adding the wall when the fire department arrived.
Oddly enough, the hard disk survived this abuse, with all data intact!
~REZ~ #43301. Who'd fake being me anyway?
This article from the latest Rocky Mountain Institute Newsletter highlights a cool biomimicry based design that looks cool and may be better in terms of noise and efficiency.
Maybe I'm missing something big here, but even the mention of 'magnetic' and 'computer' brings to mind crashed hardward and lost data.
If their marketing plan works, I think I'm going to develop a line of Tux fridge magnets -- they look great in the kitchen and stuck to your tower in the office.
Chuck
Failure is not an option. It comes automatically enabled in every Microsoft product.
As the filter restricts air-flow, its best to make filter quite a bit bigger than the fan.
Say you have a 80mm intake at the front, mounted to the main metal chassis. Then cut a 80mmx160mm hole in front plastic bevel, then screw in 2 80mm fab guards into the bevel & mount air-con filter foan behind the guards (mind you if you are going to modify the bevel you may as well cut a hole in the front chassis for a 12v@7v 120mm fan, so you get good cfm & good quietness)
If you have a blowhole on the side, say a 120mm fan blowhole, then you cut a 150mm hole in the side & mount a 160mm diametre 16mm or 35mm movie film tin behind the hole (the wider the better, given the clearance). The film tin should have a 150mm hole on the back & a 120mm hole on its lid. Screw the back against the inner side panel of the case, using the 4 or 2 screws that mount the 150mm fan guard you re going to have on the opening of the case. Attach a 120mm fan to the outside of the lid of the film tin, using a fan guard that's mounted in such a way (using washers or something) so its as far a from the fans intake as clearance allows. Cut a 150mm circle of air-con filter foam & stick it inside the film tin that's screwed to the side of the case - once you slide the film tin lid in place onto the film tin's back, the raised up 120mm fan guard on the fan's intake will push the filter up against the 150mm fan guard on the case's side panel, pushing it away from the fan with enough clearance so that air will be sucked throughout the breadth of the 150mm filtered hole before going through the fan. So really this is just a 150mm blowhole using a 120mm fan, where there's a movie film tin being used as a filter box, between the fan & the 'hole'.
Of course you must have enough clearance before you can use this 'movie film tin filter box' idea.
Fortunately, the lock ring isn't typically one of those "C-shaped" lock rings (and I have dealt with some real small ones before) - most of the time they are simply "press-to-fit" plastic bits, or sometimes a small rubber "o-ring".
;)
But yeah, it is like repacking wheel bearings - BTW, one other tip: Don't work on plush carpet
On another note - I recently had a fan in my power supply go out here at work on a Friday - the power supply was OK, but the fan would make this weird vibration noise - ramping up, sustaining, then ramping down. This would happen about once an hour, and was really loud.
Anyhow, I pulled the power supply out, pulled the fan, and went to work with the various tools I had (mainly a leatherman keychain). I got it apart, and could clearly see that the bearing was dry. I needed some grease.
Not having anything suitable (like, why would I carry vasoline in my backpack?), I went to my IT department, and asked around - no luck. Not even some WD-40 (not that I wanted to use it). So, I hunted around some more, when it hit me that our CIO, being female, might have some lip gloss or something - I went to her and asked if she had something. She told me she had some carmex - I asked if I could borrow it.
She gave me this strange look of "WTF?" - I proceeded to explain the situation, and she asked if we had any spare power supplies (we didn't). She then said "I could pick you up a fan, or a new power supply", which was fine by me. Then she said "How about we get you a new case?"...
Now, in this time of tight economies, why would you spend $70.00 on a tower case, or even $30.00 for a power supply, to effectively grease a bearing on a fan? I had the fan apart, I could get it together, no prob. I asked if I could simply use some of the carmex, and if she could pick me up a fan over the weekend, cool.
She reluctantly gave me the carmex, I took some, greased the bearing, put it back together, and reinstalled everything, and switched it on.
The next Monday, there was no fan on my desk. I never bothered to ask about it. So far, it has been about a month and a half - and my fan has yet to make another noise outside of the usual...
Reason is the Path to God - Anon
This fan could take things one step further by varying its speed based on the heat of the CPU. As far as how this would work, one idea would be to hollow out the central part of the fan and completely enclosed a small amount of liquid inside. The heatsink's heat absorption would cause the liquid inside the fan to stream up, which would in turn set the fan's speed. Thoughts?
grep >= ! == $your
when you are using your computer for digital recording. So far, my noise reduction solution of choice was to put extensions on the peripherals and have the computer in a closet or another room. This is all well and good, until you need to stick in a CD or a floppy. Plus the lack of HDD LED can be somewhat annoying, although if you are used to ssh'ing, it's not a big deal.
----
All of whose base are belong to the what-now?
How about this idea. Increase the case's width and on the side include hooks where you could mount several fans together in a kind of 2x2 grid (for large fans) or 3x3 grid (for small fans). Then daisy chain then together into one power connector.
grep >= ! == $your
That's actually scary. Anything burn up?
I wish I could get a power supply with a fan monitoring lead - my motherboard and OS (linux) both support it - but only my CPU fan has the capability.
Just because it CAN be done, doesn't mean it should!
so the air must be magnetically directed... with heat tracking technology so that your entire computer is 99 44/100 per cent pure, it will even float!
They look pretty funky, and are supposed to be about 19dBa!
:(
Check out how it works here:
http://www.pcsilent.de/en/products/veraxcpu.asp
I just wish I could afford that price
German:
www.verax.de"
Translated to English:
www.verax.de - Translated Via WorldLingo
The 512K Mac (before the Plus) also doesn't have a fan.
They do.
You can buy fans with mag-lev bearings.
One of my favorite catalogs/retailers, Cyberguys has them. Go there and put magnetic fan in the Search box; it'll pull up the fans in question, which retail for about US$10-$13.Since the site is framed I can't give the direct URL to the product, so here's some ad copy:
I'd like to use them as heatsink fans, but I think they only come in the larger 40mm case sizes at the moment (40x40x10mm or 40x40x20mm, 50x50x10mm, & 60x60x25mm).The best fan on the market is the almost impossible to get(the only retailer outside of germany that has it is www.chillblast.com, which I found out after a month of looking) Noisecontrol Silverado, which is a 2-blower silver-coated HSF, as opposed to a single-fan HSF. It is slightly below the performance of the highest-end fans now, but quieter than your crap generic cooler.
People in Soviet Russia, however, appear to be afflicted with amusing juxtapositions of the aforementioned situation
how about creating processors that dont dissipate so much heat? Like using super-conducting material instead of doped silicon anyone?
So, the bigger the fan the less energy it takes to force air through it? It stands to reason if we build a big enough fan, it would consume absolutely no energy.
Two caveats are that power consumption would only ever approach zero at infinite size, and, as you pointed out, that the fan would move increasingly slower as size increased -- but we'd still get a net positive energy (airflow)...
if only it weren't for friction. And inertia. And gravity. And thermodynamics. And so forth.
Sorry for the sarcasm. It just seemed funny.
Actually, Sun has some fairly decently (?) priced low end systems. 64 bits for a grand -- rack mounted. Only I think they still lock you in with proprientary RAM.
I asked PC Power & Cooling and their recommendation is to replace the fan with their ThermaSense variable speed fan. Runs at 20dBA/25cfm at 25C to 29dBA/39cfm at 35C. US$15.
Or you could buy one of their Silencer model P/S where they've done the fan swap for you.
And perhaps you should be worried about the magnetic fields generated by the spindle motor in your hard drive. Quick! Shut them off now to save your data.
piezoelectric... 20 seconds hmm,
Maybe "straight" water might be difficult. But how about "doped" water?
I think you're a bit confused. :-)
Let's cite for example a small airliner powered by propellers, in this case the ATR72 built by a French-Italian consortium. Originally, the plane's two turboprop engines used two four-bladed propellers; however, later production planes used two six-bladed propellers. Going to six-bladed propellers offered two advantages: 1) propeller speed can be reduced, which cuts down on noise generation and 2) since the propeller doesn't need to spin so fast it also reduces the fuel consumption of the turboprop engine.
That's why my suggestion of a cooling fan motor with a small center spindle and carefully-engineered fan blades (10 to 12 blades) makes sense. This means the motor speed of the cooling fan can be lowered compared to regular fans, which 1) extends the life of the fan motor and 2) lowers the power requirements for the cooling fan. Alas, most of the more exotic CPU cooling fans such as the Golden Orb hasn't really used modern fan blade design; in fact, much of the benefit of these exotic coolers come from the larger heatsink properties of these units.
What happened to the fans that were talked about in an earlier /. story that used positive and negative charges to blow air with less power use and almost no sound? I want some of those, not these.
[insert witty comment here]
I agree, magnets in your computer are a bad idea. (a magnet shouldn't hurt any chips, but the disk) The fact that these magnets are spinning, means that they produce lots of EM noise. This is how radio jammers work. Here are fans with out magnets: [geeknews.com] piezo fans
MAKE YOUR TIME
Yeah, apple had some problems with the first Macs, especially after one upgraded them to scsi, gave em an internal drive, etc. There were guides on how to install fans in them back then. I actually have the original Mac Bible, and it talks of building a chimney on top of the Macs, to increase airflow (since the hot air would rise up the chimney faster than it would if it just had to rise from the top of the computer, and in rising faster, pull in cold air faster, etc.) for those people who didn't want to put a fan in their computer. Quite a spiffy idea really.
I don't know exactly what model this was, but the Great Mac Fire happened about 1992, I think. The chimney idea sounds rather nifty indeed, and ISTM could be readily implemented in a full tower today to generate some extra airflow without much decibel penalty, and maybe even without a visible chimney. Anyone done this lately?
~REZ~ #43301. Who'd fake being me anyway?
12 blades weighs twice as much as six. That requires *more than* double the energy to spin. Unless you make them smaller. Or reduce the angle. Both will decrease the proportionate airflow.
While the case of one particular airplane engine may have benefitted from an increase in propeller blades -- notice they didn't up it to 12 blades. Also notice that most engines still use two or three. There is always a mean. That's why they invented calculus.
As was posted by others, the center of the fan doesn't push that much air, so reducing the spindle size, or moving the turbine to the outer edge doesn't help.
So yes, I am confused.
Well, to give you an idea, a 3 foot high chimney, which was a 2 inches a side smaller than the size of the original mac, gave what was considered optimum cooling. So i don't think it would be possible to do it and not have something visible.
But having something that ensures a flow of cooler air onto the processor would probably be more effective, allowing for fans that aren't as loud. Apple actually does something similar in the current powermac G4s (there is a hood over the cooling fan for the processor that allows the fan to pull air in from outside the computer).
For a totally quiet computing experience (and a high powered computer) a simple water cooling solution on an un-overclocked system would allow one to remove all fans from the various areas around their case (cpu(s), various chipsets, hard drives) and inside give one single surface that would need to be cooled (the radiator). Actually, I guess if you got a large enough radiator, you could use a chimney on it, inside your case, but it would have to be really big (the radiator) which means more water to move, which means a bigger pump which could make more noise.
The energy required to spin a fan is mostly going into resisting air drag. More blades = lower velocity for the same airflow.
As drag increases by the cube of velocity, with some higher-order turbulence effects, a fan with more blades is more efficient.
Take a look at the 100+ blades driving the compressor in a jet engine next time you get the opportunity.
"We have to go forth and crush every world view that doesn't believe in tolerance and free speech." - David Brin
I suppose you could also have open tops on your computers and put them all under a hood, with a long chimney and an outside vent. Imagine the draw in a windy area. :)
:)
I'd imagine a radiator could be set up like a like the ammonia fridges used in travel trailers -- use the CPU as the heat source to expand and move the liquid thru quarter-inch metal tubes, with a chokepoint and nozzle for cooling the liquid by expansion. Then run some coils from the chokepoint thru the areas you want to absorb heat from, and put the rest of the coil outside the case to let it air-cool, then back to the nozzle for another round. This is good for about 50 degrees of cooling a space of 5 cubic feet using ammonia, so I'd think a plain water system would be sufficient to cool a much smaller space like a standard tower. No fan or motor required at all. (I once had one of these ammonia fridges, so I know of which I speak. The only sound is a faint hissing from circulation in the pipes.)
With desktop cases and smaller towers, the majority of cooling actually takes place by heat exchange thru the metal case-- not via the fans at all. Cover the top and sides (leaving the fan holes open) with a blanket, and see how quickly your system overheats! Conversely, with such boxes you can get away with NO internal fans, so long as you have a fan blowing across the case itself.
I used to cool my campstove-emulator 286 that way whenever its power supply fan died and I hadn't yet got around to finding a new one. And that critter ran as long as 22 months without a reboot, let alone a powerdown. Nowadays, during the summer months I set a room fan to blowing at the newer machines, because the external airflow makes a world of difference in how hot they get.
Amazing how creative one can get if one's case fans die
~REZ~ #43301. Who'd fake being me anyway?