Slashdot Mirror
Underclocking for a Quiet Machine?
The Fun Guy writes "I'm running a PIII 600MHz, which I'm thinking of upgrading. If I could get rid of the fan and run more quietly, I'd love to. I run office-type apps, so I don't need the fastest processor around, but I also run d.net, so I'm constantly pegged at 100% usage. Aside from the obvious fact that your CPU is running slower than the listed speed, is there any downside to buying, say, a 1.8GHz chip and running it at 900MHz without the fan? Any experience or FAQ's to share on this?" We've covered this topic several
times
before, with some good feedback, however most of the approaches don't discuss the use of underclocking to accomplish this, although one common suggestion from the comments is to use a non-Intel processor, if you can. Have any of you tried underclocking your CPU to allow it to run silently? How far do you need to underclock a processor in order to enable it to run without a fan?
A C-64 plugged into my television. Silent, swift, and about the most supreme platform for Fort Apocalypse.
Fuck that high falooting stuff. There's some halfassed word processor that'll work just fine for this beast. And I'm not joking about this shit.
Here's a real (non trollaxor) link to a site dedicated to silent computing....
http://home.swipnet.se/tr/silence.html
I say take a break from the computer room, or use a laptop, or maybe turn the computer OFF every once in a while if you don't like the noise, but hey, to each his/her own.
Wow! This must be a PERSONAL letter, just for me!
A 1.8GHz processor running at 900MHz is going to let off as much heat as a processor in the same family rated at 900MHz...
Umm, yeah, right, you don't know much about CPU design these days do you?
Discounting the above, my own real world experience has been that Intel CPU's can typically eliminate the fan with a 20-30% underclock. AMD is almost not worth it needing at least 50% underclock. Also you NEED the biggest darn heatsink you can find and I strongly recommend active heat monitoring and some sort of automatic powersaving idle/shutdown/whatever if you leave the machine alone for long periods. Somebody mentioned large heat-sinks being close to the power-supply fan intake, this is a good idea and can be accomplished by using a duct (and possibly some judicious cutting) if your power supply vents are inconveniently situated.
- cpu fan
- disk drive
- case fan
- video card fan
- power supply fan
- cd spinning
Ok, so my way of solving the problem doesn't involve underclocking, but it works better:I put the computer in another room.
Get a good monitor cable (one with ferrite cores) and a keyboard extension cable and run them through a wall to the computer in another room. Now *that* is quiet. And it costs maybe $50.
Now to be honest, that's not exactly my setup. I actually have a KVM switch and hook to several computers in the next room. I have a nice quiet bedroom with a keyboard, monitor, speakers and a usb KVM switch. If you look at http://www.belkin.com you'll find kvm switches that switch audio too.
Several people on the Silent-PC mailing list have underclocked and under-volted their systems, but I don't think anyone has been able to run a modern CPU such as an Athlon or P4 without a fan. Some people have reported success with older Celerons and K6-2s, however.
You could also buy a CPU that can run at 933MHz without a fan, the VIA C3. It's pretty good, but the FPU is quite anemic. Personally, I think it's a small price to pay for some peace and quiet.
Ian
I have an 1800xp underclocked from 11.5*133 @ 1533mhz to 7.5*133 @ 1000mhz. With an MC462 heatsink and a tube fixed to the heatsink an exiting the top of the case and no fan, the CPU never exceeds 32 degrees celsius. The real test is to see how far you can drop the CPU voltage before instability arises. Mine is running at 1.65. Lower voltage plus lower frequency means less heat but remember I am using one of the highest rated heatsinks available. At 789 grams, this heatsink weighs almost 300 grams more than any other heatsink you can buy.
And yes, the chimney effect of the tube makes it feel like there is a fan blowing hot air, just like the G4 cube.
If voting were effective, it would be illegal by now.
I've seen a huge amount of discussion over the past few years about doing things to computer cases to deaden sound. Now, one person in this discussion started thinking outside the box, talking about his putting the computer into the next room and running cables through the wall -- effective to some extent, but absolute hell when you have to put a CD-ROM into the drive, don'tcha think...
What I've been looking to do is build a proper sound-controlled cabinet for my computers. It would be an enclosed cabinet with doors, fans (ducted at inflow and outflow ports with sound-proofing material) to ensure enough air flow to keep internal temps down, built-in power distribution, built-in Ethernet (I have a 24-port 100-base T hub), and sound-sealed cable ports for the KVM switch and external connections.
Some design points:
The cabinet needs to be deep enough so that the system units will have adequate front and rear clearance for airflow. Experiments with standard cases tells me that you need at least four inches rear clearance and six inches front clearance. The extra clearance in the front is dictated by CD-ROM and DVD-ROM drives, so that the door of your cabinet doesn't interfere with the CD/DVD-ROM tray. Given that the deepest cases are about 20 inches, that means you need an inside depth of 20 + 4 + 6 = 30 inches. Plan on 36 inches of depth for the outside dimension
Your primary sound barrier will be dense material, such as plywood. If you can get birch plywood, this will give you better sound control because of the increased density of the wood. It's tempting to go very thick, but 5/8 inch should be plenty good. Consider using 1x6 for the framing, and be sure the plywood is braced at least every 18 inches with framing.
Most acoustic treatments will require about two inches of depth in order to be effective across the "band of annoyance" (200 Hz to 4 kHz). Thick-pile carpeting (make sure it's flame-retardant!) can be surprisingly effective, and cheap when purchased as end-rolls or remenants. Fiberglass batting and rock wool are also effective, although the stuff is tricky to work with safely. For the sides and the rear wall, standard acoustic tile or ceiling panels can be effective. For ducts, the goal is traverse absorption, so materials like acoustic tile may not be appropriate as they tend to best absorb sound hitting the tiles perpendicular to the surface.
Design the airflow so that air deflects around sound baffles; this prevents direct ray-path propagation of unwanted noise. For example, an air intake can be done by using a front floor-level opening, a baffle panel of burlap-covered 1/4-inch plywood, and a 5/8-inch plywood shelf for the computers that stops six inches from the front of your cabinet. This design directs the airflow to the front of the computers, which from most cases seems to be the most desirable. A similar baffle system at the top of the cabinet can serve to exhaust air, again using baffle panels to break up any direct ray paths.
Any air-motion equipment should be suitably baffled as well. Large low-RPM fans work better than small high-RPM fans.
Finally, cable ports need to be sealed acoustically. Consider rubber gasket material, or the "tube foam" you can find at some fabric shops.
For my prototype, I'm using a rack cabinet I got at an auction last year. The metal skins (including the top one) is replaced by 5/8-inch plywood, faced on the inside with long-nap carpeting. The air intake at the bottom of the cabinet uses exactly the baffling technique I described above, using burlap soaked in fire retardant. Air exhaust is still a problem. Cables go through two slots in the back of the cabinet. The "door" is currently a removable panel of carpet-faced plywood, but I have designed a quad-door arrangement - this lets me get access to the CD-ROM drives without opening the entire front, yet provides for service access easily.
Temperature monitoring is a bit of a problem right now, a problem I hope to solved via eBay.
When I have more, I'll put it on my Web site and let you all know about it.
(One thing: I'm a bachelor, so I don't have a wife to worry about. Your mileage may indeed vary.)