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Efficient Power Supply Contest
A reader writes: "In the June (paper) issue of Scientific American, there is a mini-article descibing the energy being wasted by power supplies in computers. Those things are only 60-70% efficient in converting line-voltage AC to low-voltage DC, and there are so many millions of them out there that a modest efficiency increase could trim $1billion or more from the annual energy costs of the USA. Well, various governmental agencies are seeking to get improved power-supply efficiency into the marketplace. The central "clearinghouse" site is at efficientpowersupplies.org, and details of their contest are in this PDF."
I'll give 2:1 odds its down before 10 comments are posted...
Please enjoy Google's version of the main page (efficientpowersupplies.org)
Please enjoy Google's HTML Version of the PDF.
I promise no Karma Whoring, courtesy of your (sometimes) friendly AC :)
You can also check out power supply reviews on Silent PC Review. They concern themselves with efficiency since an efficient power supply can be quieter and produce less heat.
The site also has a lot of other good info.
Energy costs at a company I worked for in SiValley were becoming such a factor that they dropped the use of all CRT monitors and towers in the work place. They switched us all to thinkpads. Now, on a small level this is very inefficient, but from a large perspective, I am assuming the energy cost savings would be enormous. My tower/crt costs me at least $25+ per month at home. I could easily lease a lowlevel laptop for that.
Aj
GroupShares.com A free and interactive stock market community. It is just getting started so check it out!
-------
artlu.net
Great idea! There are so many things that we keep doing in a wasteful and inelegant way just because it's "good enough" (or at least was in the past -- when things get wider distribution, problems are magnified).
Power supplies are a good example, as are cars (so much wasted energy -- hybrids are better in that regard, though, like in converting braking energy into electrical energy that can be re-used later to help the engine when it's at its most inefficient RPM levels).
Treehugger? Treehugger... Treehugger!
especially since i use several UPSes which add another layer of inefficiency.
i want an efficient AC to DC UPS which connects directly to a DC powersupply for my box(en).
that would rock.
don't get me started on an entire DC house running off of a fuel cell and/or wind/water generators. woot!
Also one should take into consideration someone using a 500W is only getting 350 at 70% effecient. If you had a PS that was 90%, you would only need a 400W.
Now that you have a smaller PS, you might could drop a fan or two. This now decreases your power load on your new 400W.
Savings on effeciency == savings everywhere
Does anyone have anything to say about the efficiency of wallwarts (those small powersupply bricks)? What about having them plugged into the wall but not plugged into any device?
Switching supplies can approach 90% efficiency if they are carefully built. Such supplies will cost more, naturally, but an improvement from 60% to 90% efficiency will save you the extra cost over the course of a year or so. And, of course, you can feel better that you are contributing slightly less to carbon dioxide emissions.
How much extra spent on power supplies? High efficiency, high-current (500W+, where PC supplies are headed) are not cheap to produce.
It would be far better if government worked to reduce the amount of petroleum being consumed through initiatives to encourage telecommuting, locating companies in locations that don't require commuting in the first place, and research into fuel cells and hybrid vehicles.
..don't panic
They keep my bedroom warm in the winter without kicking on the furnace, and the fan blowing air over them masks the street noise outside.
The Opportunity Power supplies are one of the crucial building blocks of a modern society, converting high-voltage alternating current (AC) into low-voltage direct current (DC) for use by the electronic circuits in office equipment, telecommunications, and consumer electronics. Over 2.5 billion AC/DC power supplies are currently in use in the United States alone. About 6 to 10 billion are in use worldwide.
While the best power supplies are more than 90% efficient, some are only 20 to 40% efficient, wasting the majority of the electricity that passes through them. As a result, today's power supplies consume at least 2% of all U.S. electricity production. More efficient power supply designs could cut that usage in half, saving nearly $3 billion and about 24 million tons of carbon dioxide emissions per year.
The Purpose of This Web Site This Web site was created by EPRI PEAC Corporation and Ecos Consulting to initiate a global dialogue about energy efficient power supplies. Our focus here is particularly on the issue of energy consumption in the active or "on" mode of product operation. According to our research so far, nearly 75% of all the energy used by power supplies occurs in active mode. For those interested primarily in standby power consumption or other low-power modes, please visit Lawrence Berkeley National Laboratory's Web site on that topic at http://standby.lbl.gov.
The California Energy Commission's PIER (Public Interest Energy Research) program has funded Ecos, EPRI PEAC, and the Energy Innovation Institute (E2I) to assess the efficiencies of modern power supplies and recommend strategies for improving them. An open exchange of design information, test methods, measured results, and other related documents is essential to that project's success, tapping the best information available from manufacturers, government agencies, utilities, and product users.
In addition, Ecos and EPRI PEAC are working on a variety of other power supply efficiency initiatives in the U.S., Europe, and Asia, described in more detail under Projects. Our goal in every case is to accelerate the market for more energy-efficient products, saving energy and preventing pollution.
How You Can Get Involved
Chaos will always win out over order because chaos is more organized
What if the same idea where applied to computers. Right next to the standard wall outlet would be a world standardized jack with six or eight pins for each of the required voltages.
Low voltage computer mains would make UPS systems less complicated too.
I've even heard of vendors who make telco friendly rackmount PC's that take 48v DC mains.
This is a boring sig
The power supply in my S-100 bus Z-80 computer weighed about 20 kg. Apple was one of the first microcomputer companies to use switching power supplies.
Mea navis aericumbens anguillis abundat
I was under the impression that a 400W power supply was capable of outputing 400W of power, not that it took as input 400W of power.
Casual Games/Downloads
http://www.mini-box.com
by switching from energy guzzling CRTs to cool power efficient flat screens. I went from a 19" CRT at 350w to a 19" flat screen at 50w quite painlessly.
I doubt you could achieve that kind of savings no matter how power efficient you made the PS.
Reminds me of the one about the Canadian Government buildings being determined to cost $200 a year per sq ft to maintain, so they replaced the CRTs with LCDs because they used less space, and therefore would cost less to maintain.
*sigh*
If you could be told what you can see or read, then it follows that you could be told what to say or think - BoC
In short, there is almost NO reason to not use those fluorescent bulbs and it would result in a far greater amount of energy savings right now...
Every electronic doodad I can think of has an AC/DC adapter. It's not just an issue with computers.
And it would be nice to get rid of those bulky AC/DC power bricks too...
Carl
Vote Libertarian
[wallwarts with the load unplugged] are still converting even though it's more efficient than normal since there is smaller load.
Actually, they're LESS efficient than normal. With no load, ALL the power they consume is wasted - efficience is 0%. B-)
Now the total AMOUNT of waste IS typically lower. But it's not trivial. Even the lowest tech wallwart burns power heating copper in the transformer and making up leakage in the capacitors. If it has a switching regulator it's also burning a bunch of power keeping that alive. And a voltage-flattening/capacitor-discharging resistor actually INCREASES the amount of power wasted in the wart when the load is gone (by eating some of the power that WOULD have gone into the load).
So why waste ANY by leaving the wart plugged in?
You can guesstimate the power by feeling the wart when it's been sitting there with no load for a while. The hotter, the more waste.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
I really wish there were a standard 5V/12V DC interface for home/office use. If you want 60 Hz 120V AC (or 50Hz 220V AC for much of the world) you plug in your device into a standard power connector (ignorning the us, uk, and european connector divergance). Anyway, if you are like me, you probably have about 20 little wall warts (smallish DC power transformers) plugged in under your desk. Wouldn't it be wonderful if there were an ANSI/ISO standard 5V/12V DC power bus that all these devices could plug into? Imagine the joy of not having 20 wall warts plugged into 4 power strips under your desk!
-Erik -- --This message was written using 73% post-consumer electrons--
I remember measuring the power factor of various serverers that we were evaluating at come point, and discovering that it will vary greatly between cheap and expensive servers. Some of the cheapo ones had a pf of .4, while high-end Intel server have a pf above .9. The interesting thing is that most people (even and especially those that sell and service computer hardware) don't even know what pf is and why it is important (unless they are electrical engineers or have been directly involved in building large computing facilities where it directly impacts the cost of the electrical infrastructure).
I'm a professional engineer, and have done several designs of switchers that were better than 95% efficient. But they cost more to make, so dream on, it's not going to happen in the mainstream with out some sort of mandate. The tricks are simple, better inductors (cost more for bigger copper and more ferrite), synchronous rectification (fet and drive costs more than a diode), taking care to be clever about quiescent currents (more engineering time) and so forth.
Doug Coulter, owner
C-Lab
http://clab.mystarband.net
Switching supplies can approach 90% efficiency if they are carefully built.
A downside of high efficiency is that the energy lost to heating is a tiny fraction of the energy handled. When certain components start to fail they can increase their losses - and this increases the heating. The higher the overall efficiency, the greater the extra heating is as a percentage of the NORMAL heating.
If this is not taken into account in the design of the supply (and its cooling budget), the supply may be prone to thermal runaway and catastrophic failures as components age.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
it's a law.
That maybe the case, but it doesn't change the basic logic. If a 500W is 70% effecient, then it is pulling in 715W. If 500W is what you need, then at 90%, you now only need a PS that pulls 555W. Dropping almost 200W from your input, decreases your heat, decreases your fan requirement, decreases your output (and therefore input) requirement. See?
You're way off. In 1994, the U.S. alone produced over 1.3 billions tons of carbon (not CO2, just carbon; the CO2 weighs even more than that).
while about 500 million tons were produced by natural causes.
Natural causes do not "produce" CO2. They merely recycle carbon. The CO2 emissions of living organisms have no net effect on the global carbon balance, because all they are doing is moving it around, from the atmosphere into the biosphere and back again.
It is true that methane emissions from cows are an issue. This is because methane is many, many times more effective than CO2 at trapping heat. But the net amount of carbon still remains the same.
All the 'inefficiency' in your computer gets emitted as heat, noise, RF or light.
Ultimately, most of the non-heat forms of energy loss get turned into heat in the surroundings when they get absorbed by something, like a wall.
So if you are trying to maintain your house at a higher temperature than it is outside, then all the lost energy from your computer goes to do useful work heating your surroundings. Hence a 100% power efficient computer.
Now if we could efficiently generate electricity, we might have an efficient total system. I don't see that happening soon.
Evil people are out to get you.
OK lets say your PC is drawing on average 300 watts not to hard to do with a modern machine. At 15 cents a kwh over a month thats slightly more than 32 bucks, my laptop maxes out at 60 watts and thats charging the battery it's normaly about 30 or a thenth of that figure but even at may I would be saving 26 bucks a month. I live in the north east so the cost is a lot higher than average here the best I could find was 2001 data that put it at 8 cents national residential average.
No sir I dont like it.
The official model of the US, put in place by the Founding Fathers, is "E Pluribus Unum" or "Out of many, one". The founders did not share the philosophical view of Ayn Rand, and creating a state was exactly what they were committed to.
Besides, energy efficiency is a national security interest. Over-dependence on oil imports means the US is more likely to engage in foreign wars.
Some large buildings have very large flouresent ballasts in the basement (or where-ever) because they can more effectively provide that power as a large unit rather than hundreds of small units.
What if the same idea where applied to computers. Right next to the standard wall outlet would be a world standardized jack with six or eight pins for each of the required voltages.
Computer supply voltages are VERY LOW - and trending lower. That means, for a given amount of power, their currents are VERY HIGH. Losses in wiring (for a given size of wire) go up with the SQUARE of the current.
The result is that you'd need to wire such outlets with fat copper bars, rather than "wire", to avoid losing far more in the wiring than you'd gain in the improved power supply in the basement.
Computer requirements (especially voltages) are rapidly changing, the voltages have to be well regulated (meaning you need regulation after the outlet anyhow), and a lose connection interrupting one of the set of voltages can be big trouble. So you're stuck with power supplies in the box.
(Indeed, makers of some high-reliability networking devices, including the company where I work, put a set of power supplies on EACH CARD, rather than depending on a redundant pair in the box to power all the cards.)
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Last night, while I was out watching my power meter spin and spin and spin... It got me thinking about a digital whole house power meter that I could monitor. I want to be able to get a true RMS power meter that can measure 100+ amps AC, and outputs the data somehow. I'll write a little app to track and graph it, and work on lowering my overall house power usage.
:)
Todd
Anyone know of such a device? There are industrial ones out there, but I haven't seen a reasonable priced one for household use.
Hey, I am an electrical engineer; maybe I should just make one.
Assume 100 for the crt and 150 for the tower. Assume the crt is own 10 hours per day and the tower is on 24 and power costs 0.10 USD per kw/h.
.10 is 0.44 USD per day or $13.33 per month.
( 100 * 8) + (150 * 24) = 4400 Watts or 4.4 kw/h
4.4 kw *
I was way high.
It's worth mentioning also that most are rated 400W max. Much like CD-ROMs (40x max), speakers (150W Max vs 30W RMS), etc it is a measurement of peak and not nominal output.
That being said, even currently all PSU's are not created equal. A decent 400W will power most computers very nicely, with closer to the rated output. A cheap PSU will die, or cause anomalies, or just not do the job as well.
While it's not always true that heavier=better... if your PSU is quite light then chances are it's a cheapy, and you aren't going to often get near the "max" rated output.
I wonder though, if the better PSU's are also more efficient in this manner as per the draw from household current?
Out of many (states), one (nation). Basically this statement refers to the representative government (republic) that was established, not a pure democracy.
It has nothing to do with the role of the citizen, let alone imply any obligation of citizens to a collective.
Though we do agree that energy efficiency is indeed a national security issue.
"Ask not what your country can do for you." --John F. Kennedy
Three cheers for liberals and a centralized federal government, then! Without them, the city streets wouldn't have lamps--let alone the power to run 'em--and we'd all be walking down long, dark...
Um...
Obliteracy: Words with explosions
That's not a totally inane rational.
Each worker needs a minimum amount of space to get their work done. My two old CRTs took up my entire desk, requiring me to have another desk in order to do any work that required paper. The new LCDs have freed enough space on my desk that I can use it for both purposes. This would allow them to mandate removal of my other desk and reduction in size of my cubbyhole.
If everyone's space needs can be reduced by a few square feet, we can pack in more people without the current occupants feeling more squished. Alternatively, we can improve the working environment for cramped people without actually investing in new office space.
Thus if I save 2 square feet at $200 per foot, I can actually justify spending $400 on a new monitor. I can spend more on monitors for workers in space limited work areas.
This is not a political statement. This is not legal advice. It's a frick'n Slasdot post. However: I'm Running For
Not to mention the money you save on light bulbs...
How can we continue to believe in a just universe and freedom to eat crackers if we have no ale?
Nobody except liberals consider 'the annual energy costs of the USA'. People do (and should) consider THEIR annual energy costs. [...] The USA is not the Borg, and no country should be.
Bravo.
Pointing out the "central planning" aspect of the press release highlights its futility.
If the central planners had been thinking more clearly, they'd have been lobbying for power-supply efficiency labeling, ala the energy-usage labels on major appliances such as furnaces, water heaters, refrigerators, and the like.
(Disclosure to the individual purchasers of the information necessary to make informed choices, in a standardized format, puts the market forces to work constructively for all concerned. It's an intervention that even minarchists can often find it in their hearts and ideologies to forgive. B-) And a case where even an inadequate standard can be better than none.)
But of course the liberals don't think that way...
Mod me down, and I will become more powerful than you can possibly imagine.
Having already commented elsewhere in this thread, and reviewed your recent postings on other topics (which often bring up insights others have missed), I've decided to mod you "friend" for a while. B-) (Let's debate Godwin's Law some time. IMHO it's all too convenient for neo-NAZIs.)
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
It's called a "marine battery." You ditch the internal power supply and feed DC from an external battery (through a voltage regulator) directly to the motherboard. I essence you've now turned your desktop into a descrete componant laptop (for sufficiently large values of "lap"). It's really not that hard.
Now, since you're never running on anything but battery power, you don't need most of the functionality of the common UPS. Your computer's own power managment takes care of all that.
And the beauty of it is exactly where you say it is, you can now draw your energy from any source that can produce electricity. That could be a battery charger plugged into your wall socket, or it could be a solar panel sitting on your cabin top, a small wind turbine sitting on your taffrail, a water turbine being dragged behind, a hand cranked/pedal powered generator, or even, yes, hamsters.
It's completely source agnostic upstream from the battery.
Your case is also smaller and cooler, but your "UPS" is no bigger or heavier if you already use an "enterprise class" (warp overclocking Mr. Sulu!) UPS.
Frankly, so far as I can tell, the only reason we do it the way we typically do it (if you're not a boater or RVer) is because we've always done it that way. We've declined to reinvent the wheel when such might actually be appropriate, chosing instead to add wheels to the existing wheels in extending chains of Rube Goldbergesque functionality.
KFG
You would STILL need heavy busbars with 12VAC, for the same reason you would need them with low voltage DC--VOLTAGE DROP.
Also: Heating. It's the CURRENT that heats the wire. The limit on wire size in a wall is keeping the heat down enough that it doesn't set the walls on fire.
Your house is wired with #14 for 15A circuits, #12 for 20A, #10 for 30A.
At 120 volts a puny 15 amp circuit can provide 1650 watts, enough to run a space heater with leftovers for a couple 75 watt bulbs, or all the lights in several rooms. 20A will feed several motorized appliances or your whole computer room. A dual 30A feed easily handles an electric stove and oven, or an electric drier.
At 12 volts a 20A feed would be maxed out by four 60 watt desk lamps or a couple 100 watt ceiling lamps. (Forget the toaster.)
Yes, you'd need bussbar. Every 12V circuit would require TEN TIMES the amount of copper as a 120V circuit to provide the same amount of energy with the same percentage of it heating the walls.
That goes for the line cords, too.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Well, Yes.
But to produce that full output of 400 watts at 60% (0.60) per cent efficiency it will consume 666.666 watts, dumping 266.666 watts as waste heat.
More important, *Please note also* that the power supply reaches maximum efficiency at rated output, I.E. at outputs less than rated, the efficiency can be a LOT LOWER than you think.
Bring the USA into line with the rest of the world and use 230VAC instead of 110V. This halves the current through the wiring, thus halving the power wasted. And cables need only half the copper for the lower current, saving raw materials into the bargain.
That's pretty much what modern switching power supplies do! If you were to examine the circuitry in (for example) the typical PC power supply starting from the AC input you will find a safety fuse, line filtering, a bridge rectifier, and a large storage capacitor. At this point the AC input has been rectified into high voltage DC.
What follows is a large power transistor (the switching element) and a "flyback" transformer. The transistor is switched on and off at a high frequency (something like 56kHz) and this energizes the primary side of the transformer.
The secondary side of the transformer has multiple taps, each tap responsible for one of the common voltages used in a PC (3.3, 5, 12, -5, and -12.) The taps output pulses so there is an additional rectifier and filter network (usually consisting of an inductor and capacitor) on each output from the transformer. One of the outputs (usually the one with the highest expected load) is monitored by the switching regulator control circuit. The controller adjusts the duty cycle (pulse width) of the switching transistor to regulate that monitored output voltage.
The other voltages (the non-monitored voltages) often have "post regulators" which can be linear or switching types. So, for example, the "-12" from the flyback might actually be -14 and there is a linear post-regulator to keep it at -12. In really crappy (common) PC power supplies they just leave out the post regulators and specify that the monitored output has a tight tolerance (example, 5V +/- 5%) where the non-monitored outputs have wide tolerance (12V +/- 10%) In such a power supply, the 12 volt (non-monitored) output will vary widely based on the load present on the 5V (monitored) output.
The efficiency of such a power supply varies widely based on details of the design. It is possible to design a highly efficient switching power supply (example, 90% efficient) but such power supplies are generally a lot more expensive. Some techniques to increase efficiency include:
* Instead of the multiple-tap flyback transformer, use a separate transformer for every output voltage or at least for every output voltage that has a significant load. So, you might use completely separate regulators for the 3.3, 5, and 12 volt outputs. The load on the -5 and -12 is usually quite small so these don't warrant fully independent regulators - linear post regulators are fine. The disadvantage of using truly separate regulator circuits is that N times the amount of circuitry is required which drives up cost and physical space requirements. Better PC power supplies actually have 3 regulators: one for the +5 standby (relatively low current, always active), one for the combined +5 and +3.3, and one for the +12.
* Increasing the switching frequency of the regulator can also increase efficiency. One problem is that better quality components are required - in particular the transformer and switching transistor. Also, the circuit layout is much more critical as the switching frequency is increased. Circuit layout can be a challenge when a design must fit an existing form factor (such as the shape of a typical ATX power supply.)
* Power factor correction (there is both active and passive types.) Power factor correction attempts to shape the utilization of energy to match the AC waveform. You can imagine the problem: without power factor correction, a switching regulator consumes energy in high frequency pulses that do not have any relationship to the AC waveform. Passive power factor correction essentially adds a filter network to the AC input. In active power factor correction the switching controller "knows about" the AC waveform and can adjust pulse width best utilize this. Some of the better PC power supplies (the more expensive ones) have active PFC.
Here is one example of a DC-input ATX power supply. It uses 24V in, so it's up to you how you want to mix'n'match utility AC and alternate DC sources. For more general info along those lines, check out Home Power.
--The more you know, the less you know.
No, your question and your understanding was valid. The power rating on a power supply states what maximum power the supply can deliver to its load. The actual power consumed *from* the power supply is solely a function of the load attached to it (i.e. the "computer" components it runs). The actual power consumed *from* the wall outlet is the sum of the power consumed by the power supply's load (i.e. the computer components) plus the extra power consumed by the power supply (i.e. the waste) which is directly proportional to the power supply's efficiency.
WarriorPoet42 got it right the second time around - but this did not make your question "stupid."
BY THE WAY: Just because you have a 400W power supply in your PC does NOT mean you are consuming 400W of power from the AC outlet. If you put an older (slower) CPU/mobo with no expansion cards, and run, say, a modern low-power hard drive, etc., the LOAD presented to the 400W power supply will be much lower. Think about it. Small form factor PCs are often built with 150W power supplies. This means that the components NEVER consume more than 150W, and probably seldom if ever hit that peak.
A side-effect of this is that the power supply efficiency does not necessarily always *waste* its ratedpower-minus-(1-minus-efficiency).
(whaatt??) Let's say:
R is the power supply's rated power.
E is its efficiency expressed as a fraction of 1 (i.e. 90% efficiency is expressed as 0.9)
So, a 400W (R=400) power supply with 80% (E=0.8) efficiency will *waste* 400*(1.0 - 0.8) 80 watts of power. But ONLY if the LOAD is drawing the full 400 watts of power!
Now let's say we have a 400W power supply with 80% efficiency, but the computer components only draw 180W of power. Let's use C to represent the power draw of the computer, so C=180. Now, just substitute C for R and you get:
C*(1-E) = 180*(1.0 - 0.8) = 36W. This is what you are REALLY losing due to power supply inefficiency.
Note: A switching power supply will have some minimal losses even if there is NO load attached to it. These are small compared to the efficiency losses in normal operation, so for practical purposes may be ignored. You could add a constant (say, K) to the equations above to account for this static power loss in the power supply, but K would be small, when compared to C, so has little effect on the math....
You'd think so but:
When a wall-wart, or most any power supply is plugged into the wall, the first thing the power connects is a transformer, and then goes directly to the wall. It is 100% all the time connected to this transformer, and conducting current through it, even though the device on the other side of the transformer isn't picking up any juice. A transformer is just two coils spun together around a common axis. Both coils have inductance and resistance, and the "main" one is always powered as long as the device is plugged in.
Now, switching supplies are a different story. They use a transistor (to simplify) in line with the main coil to "chop" the AC voltage up into an even quicker AC. Higher frequency voltage transmits much more efficiently through a transformer, so you can have a much smaller/cooler transformer for the same power output level. They also have the added benefit of being able to completely shut off the main coil when the secondary doesn't need any (with some supporting circuitry which always has a very small power draw, but it's much better than the always-on draw of a big coil).
-Jesse
Nothing says "unprofessional job" like wrinkles in your duct tape.
Seasonic Super series power supplies. My UPS load meter registered a ~15% drop in PC power consumption after I switched to these from Antec. Highly, highly recommended.
/sys/devices/systsem/cpu/cpu0/cpufreq/scaling_sets peed to match the power/performence balance you think is best. See the Athlon 64 Processor Power and Thermal Data Sheet. For example, a current top-of-the-line Athlon 64 3800+ burns 89W at 1.5V at maximum (better than Intel, but still a lot). If you lower the clock speed by 200MHz, the chip burns 72W @ 1.4V, another 200MHz lower burns 53W @ 1.3V, and another 200MHz lower burns 39W @ 1.2V. You can cut it all the way back to 22W max, 1000MHz @ 1.1V. With the current Fedora Core 2 kernel and a power management daemon like powernowd the speed will be adjusted automagically, but if you want to run Folding @ Home without excessively spiking your electric bill it's nice to set a fixed speed manually.
Also, use AMD 64-bit CPUs and set
The Mobile Athlon 64 3200+ (62W @ 1.4V max) is interesting if you really want to limit power consumption. I put one in my ASUS K8V Deluxe motherboard (Zalman CNPS7000A-AlCu heatsink, be VERY careful not to overtighten it and crack the unprotected core as there's no protective aluminum lid like on the desktop CPUs, not all heatsinks will fit). Drop 200MHz and get 46W, another 200MHz gets 34W, and at 800MHz a mere 13W. Given that the new Prescott-core Pentium 4's burns well north of 100W, this is pretty neat. Note that since AMD's transistors have a MUCH lower leakage level than Intel's (20% versus 50%) your idle power consumption at any clock rate is going to be pretty low. Things will get even better when the new 90nm chips come out in a few months.
I was on a quest to quiet down the PCs I've got, and came across the Seasonic Super Tornado Review over at SilentPCReview.
.98 to .99. I used a Kill-A-Watt meter to measure before/after power draw and PF. The PSUs replaced were 2 generic PSUs and one Antec True Power unit.
I measured the before and after current draw of my PCs and found that the Seasonic Super Tornado PSUs were not only much quieter than the PSUs I replaced, but also reduced current draw out of the wall about 15%. Additionally, they have a PF that I measured at
The Seasonic PSUs are the most efficient that SilentPCReview has reviewed at about 80%. It makes sense that if you are building a new PC or need to replace a failed unit to spend the money on the Seasonic units. They are even competitively priced compared to other name brand PSUs as well.
60 watts for your laptop? I think you're looking at the wrong figure. That's probably the power output to your laptop, not the power input. On my laptop, the power transformer does 75W (15V @ 5A) out, but 120-144W (1.2A @ 100V or 0.6 @ 240V) in. It's between 63% and 52% efficient by those numbers. My laptop may consume less than half the power my desktop does, but it comes at a price. A poor keyboard, poor pointing device, slow hard drive, mediocre video chip and a slow response rate on the high resolution LCD.
I used up all my sick days, so I'm calling in dead.
In fact, to efficiently do DC->DC, most circuits actually do DC->AC->DC, again using a transformer to do the voltage step-up-down. A transformer is the most efficient way of doing voltage conversion (really impedence matching), at least when moderate to large amounts of power are involved, and transformers require AC to work.
Your electric meter tells how many kilowatt hours you consume. The same meter with the help of a clock that measures seconds and some simple math can show you how many watts your appliances use. The disk that rotates in your meter has a black reference mark. On the dial plate, usually in the lower right, is a conversion factor for that particular meter (for example Kh=7.2). To read watts, start counting seconds and disk rotations when you see the mark. Stop counting after a minute or after several disk rotations. The formula is watts = (Kh x number of disk rotations x 3600) / number of seconds. For example, you count 5 rotations in 64 seconds (7.2 x 5 x 3600) / 64 = 2025 watts. You can measure your whole home consumption or you can turn everything off and measure one appliance at a time. You may be surprised to see your meter turning when every appliance, including your refrigerator, is turned off. That's because "phantom loads," devices that are on even when you turn them off are still using power. Televisions, phones and answering machines with "power cubes," VCRs, etc. are some phantom loads.
I tried this and found over 200W of phantom loads!!!
What you're describing is linear regulation, and is the most basic type of power supply normally made. It's also horrifically inefficient, not because of the transformer or bridge rectification, but because the voltage regulators use transistors operating in the linear mode (hence the term "linear regulator"). If you understand basic electronics, you can think of the transistor as an adjustable resistor; it has to create a voltage drop between the output of the bridge rectifier and the output voltage. So of course, that transistor consumes power (given off as heat); the more current the load demands, the more current goes through that transistor, and the more heat it produces. Obviously, you want to keep the bridge voltage as close to the output voltage as possible, but there has to be a certain differential because of filtering etc.
Aside from the inefficiency of the linear regulation, the other big problems with this kind of supply are size/weight (because of the huge transformer), losses in the transformer itself, and the need to have a large heatsink on the regulator.
Lastly, transformers don't make computer power supplies inefficient or heavy, because they don't have them. Computer PSs use switching power supplies, which have capacitors, inductors, and transistors (operated in the highly efficient saturation (full-on) mode), and are much more efficient than the linear power supplies you referred to. However, the efficiency of switchers can vary greatly, which is what this article is all about. Well-designed switchers can be extremely efficient (like over 90%), but commonplace PC power supplies are much less efficient due to poor design and construction, which is no surprise since most people and companies buy the cheapest stuff they can.
Maybe you need a refresher on how to divide numbers. In 1994, as I've already shown, the U.S. alone emitted about 1.3 billion tons. The paper the parent poster linked to shows CO2 emissions from the biggest volcanic sources. They add to about 1 billion tons.
So in fact, the U.S. is emitting about 30% more CO2 per year than all the most active volcanic and geothermal areas combined. Worldwide human emissions are even greater.
The cheapo power supplies used in PCs cost less than a tenth of that. Many of them don't have protection circuitry and forged UL certifications are common. Most won't deliver their rated load, and many, if loaded up to their rated load, will burn out, or worse, catch fire.
The real problem is to get to 90-95% efficiency at $0.10/watt.
I have a wife & todler and live in a 5 room apt (2 br, 1 bath, kitchen & living/dining room) and we use very little power. Granted we don't have a washer, drier, water heater, or electric heat. But we pay attention to our power use.
1) our tv (27")& dvd/vcr is on an outlet run by a light switch. TV's have instant on where they are charging the capacitors all the time. ITs not like the old B&W tv's that had to warm up. Also, the vcr drains power displaying the time and what ever else it needs to do.
2) The computer stays on most of the day (7ish - 11ish), its a 200w pwr supply and I've got a raid 0+1 on 4 drives. the 21" monitor which is an IDEK iiyama from circa 1992 is turned off when we are not using it. If we leave the house for a few hours we will pwr down the computer and flip the surge protector and turn off the wap, cablemodem, printers(if on), and speakers.
3) we use the toaster oven & microwave more than the regular oven & stove top. They use way less energy. If I'm only heating up some french fries and dinner rolls it takes less to heat up a small toaster oven that a large stove. The fridge we can't do much about, its ancient, we just don't open it more than we have to. THe more it's opened the more it has to cool back down.
3) lights, we have energy efficient bulbs, they cost $0.39 each after the rebates from effiency vermont. We turn them off when we are not in the room.
4) We only have one clock that is plugged into an outlet, the other clocks in the house are battery operated and the battery will last 2+ years.
5) we unplug the wallwart for anything we it is not being charged/used.
The only things that may be left in to suck power when not in use is a radio down stairs and the one in my daughters room that we leave on at night for her.
6) the a/c in the summer time, I've insulated as best as possible around the window it sits in. I ahve it on a timer, it only comes on at night in my daughter's room to help keep her cool. It's on from 7- 12, by that time it's cooled off enough and the cold air stays in pretty well. We adjust the shades/blinds to keep as much direct sunlight out of the apartment and from heating it so we don't use fan's very much. Only when it is above 80 degrees.
So less than 200kwh per month is possible for a family and you can still watch a decent size tv & have a computer on all day. Even if we forget to turn something off or unplug something, its not that big of a deal. Plus living in a town that owns it's own electric company, I have never seen a bill for my place over 27$.
~bigmoose