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Better Power Supply Roundup

CainX writes "A comparison of five power supply units was posted recently. Anandtech has done a more complete review and examined 18 of the newest models in the plus 300 watt range." Power supplies tend to be one of those forgotten, but ever so important parts of machine construction.

18 of 196 comments (clear)

  1. Re:Power Supplys by jpmkm · · Score: 4, Informative

    I'm thinking that's a UPS. Servers usually have redundant power supplies, not one for multiple machines.

  2. Re:Power Supplys by Anonymous Coward · · Score: 1, Informative

    That's called a UPS. Not the same thing.

  3. Re:memory faults by dnoyeb · · Score: 2, Informative

    Weeks? really? Usually electronics fails in the first 24 hours, or its good to go. Especially where there are no moving parts.

    I dont think the added time is a proper measure of increased reliability.

    anyway, PSUs are overrated. I have used elchepos to the top quality units, and found differences in voltages, but not performance.

    I buy for sound now. But of course I dont run any high performance / demand servers either.

  4. Re:How much power is drawn from the wall? by wirelessbuzzers · · Score: 5, Informative

    No, that's a maximum rating. It doesn't draw nearly 400W if you aren't going to use all that, otherwise it would have to dissipate 200W on its own, which it certainly cannot.

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  5. 28 pages? Give me a break. by Anonymous Coward · · Score: 5, Informative
  6. Re:What's the deal on the Antec 330W and P4? by drwtsn32 · · Score: 4, Informative

    Agreed. IMO Antec makes some of the best power supplies. I use several Antec 330W ones at work in P4 systems.

    PC Power and Cooling is very good, but their supplies are more expensive than Antec and are usually noisier.

  7. Re:How much power is drawn from the wall? by Detritus · · Score: 4, Informative

    Your friend's parents are mistaken. Just because the computer has a 400 Watt power supply doesn't mean that it is actually supplying that much power. It is probably considerably less. Think of it like the engine in a car. It may be capable of 150 horsepower but the average power output is much less.

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  8. For anyone who thinks PS don't matter by plcurechax · · Score: 4, Informative

    I just built a new Athlon XP (2600+) based system, and the power supply was the most frustrated part to get working correctly. I bought a generic case with a 300W Pro-Power ATX power supply. It had useless regulations, the 12V rail measured at 12.8V with the system on and idle, and jumpted to 13.2V when running some math calculations that I use for stress testing (www.mersenne.org).

    So I spent a Saturday trying to find a local computer dealer open that had any power supplies in stock. Most were sold out because of recent lightning storms (note: most didn't fail right away), anyhow about 2 hours of looking and driving I found a Codegen 300W ATX supply. It didn't setup off the SilentPC power alarms, but it failed the stress testing, with errors in about 1 hour of testing. The CPU temperature was fine (40-42 C) but I suspect the power wasn't clean which introduced memory or logic glitches.

    Finally after a week, I got a ThermalTake 360W power supply and my system works fine.

    So anyone who has an unstable system, it may not be all the fault of the OS, but poor or underpowered power supply.

  9. Re:External supplies by ZorinLynx · · Score: 4, Informative

    No, this would be a bad idea. The cables from the power supply to the system would be carrying low voltages, and to provide power to the system at those voltages would require high current. This would cause voltage drop (and thus loss) in the cables.

    When wiring up electrical systems, it is important to remember that your long runs should always be done with high voltage cable. For instance, from the wall to the power supply is 120V AC. Once the voltage is reduced, the runs need to be kept as short as possible, since every foot of cable loses substantially more power at the increased current required.

    50 watts at 120 volts is less than half an amp. 50 watts at 12V is about 4A. Big difference. }:)

  10. Re:How much power is drawn from the wall? by HidingMyName · · Score: 3, Informative

    The best way to measure is probably experimentally. You could use a "Kill a Watt" device, that has a combination of a male and female plug with an output for indicating how much power is being drawn. You can get one for $40 U.S. or less.

  11. Power Supplies Affect Stability by Anonymous Coward · · Score: 2, Informative

    For you do-it-yourselfers:

    Don't underestimate the importance of power supplies, nor assume because the box says "400W" that it really is, nor assume that any particular rail - +12V, +5V, +3.3V has the current you need. Sagging voltages on any rail can have mysterious effects that you will otherwise blame on your motherboard, the BIOS, memory, cards or the OS.

    I was the victim of an underpowered power supply when I upgraded my motherboard, and of course, I blamed the motherboard. Of course, my suspicions were bolstered by the presence of a known defect in some of the boards having to do with a flaky overheating protection circuit. When I replaced the board with the same kind, directly from the manufacturer and it kept happening, I realized it must be something else.

    I did a power resource calculation using the guide on the AMD site and viola, I was running my supply at 90% of capacity. A no-no. I upped the supply from 300W to 450W (a true 450W), haven't had any problems since.

  12. ThinkGeek? You are an idiot. by rkz · · Score: 2, Informative

    If you buy from thinkgeek you are being severely ripped off, newegg has it 20$ cheaper.click here

  13. Re:How much power is drawn from the wall? by Tragedy4u · · Score: 2, Informative

    I remember my boss having power concern issues with our equipment at our co-lo facility. We had a bunch of low end RS\6000 kit that had 800W power supplies in them, thats almost 7 amps which is half the usage of most vaccum cleaners! It didn't seem right, these were older machines and not very powerful they couldn't possibly use that much power, so we grabbed a multi-meter to check the usage. On boot up (the most expected), the usage spiked up to just above 1amp (filling the capacitors I imagine) then dropped quickly down to about .5 amps thats the equivalent usage of an average light bulb 60Watts.

    Unless your friend is running a server with lots of SCSI hardware and doing very CPU and disk intensive activity all the time, I'd imagine that his power usage would sit around that ammount.

  14. Design Engineer, Power Supplies, Computers by lcsjk · · Score: 5, Informative

    As one who has spent some 16 years designing power supplies for computers and other devices, I found the article to be very weak in factual information.
    Power supplies have an actual efficiency of about 75%, and no better than 90%, no matter what brand, Efficiency varies with loading.
    Quick spin-up on hard drives takes about 5 times as much 12V power as is required for running, but little 5V change.
    The actual voltage needed by components is not nearly so critical as the amount of noise (ripple and "switching" noise. (These are switching power supplies.) The nearest thing to a noise measurement test was the memory test.

    Output regulation is also dependent on the loading of the 5 volts or 3.3 volt outputs. Expect the 12 volts to follow the 5 volts as the processor and MB requires more or less computing power during operation. Some are independent, but most are not.

    Things like temperature testing can be very meaningless. Most components are designed for operation at an ambient of more than 70 degrees Celcius. The switching transistors will produce the most heat, but a small capacitor setting downstream in the airflow may be the first long term failure. Probably input to output is the best indication.

    Note also that the power supply fan sucks hot air from the PC and sends it over power supply components before exhausting to the outside air.

    The one test I found most interesting was the memory test, and although I am not sure of the methods used, the results do indicate overall performance. (Yes, I have also designed memorys and been involved it testing of memory chips with walking ones and zeros and checkerboard patterns etc. Without knowing which row of memory transistors is adjacent to the one being used, pattern testing is basically meaningless except for one word at a time.

    A few years ago I took a Sparkle (SPI) power supply and a Fortran power supply apart and the insides were identical - completely. Fortran was about $3 more in hundreds at the time. My guess is that they were made on the same production line. Are they the same or had one just been copied.

    The power supply continuous output rating should be the one used when talking about a 300 watt power supply, not the power line rating.

    Finally, audible noise. Bigger fans, lower speed, less noise. Fans mounted on the inside instead of near the back panel produce less noise.
    Fans blowing onto holes instead of through a circular guard produce more noise.

  15. Re:How much power is drawn from the wall? by evilviper · · Score: 3, Informative
    There should be some device he could pick up at a local electornics store that could measure the amount of power the machine is using right?

    Search froogle for "Kill A Watt". I've got one and it works surprisingly well. Good luck finding it at any stores nearby. It's even a bit of a rarety online. (Check solar or radio shops)

    As I posted in a reply to his comment, my XP 2000+ is using up almost exactly 100watts, obviously that may vary a bit, but not much. Even an old 166MHz system of mine is using up about 60 watts. Interesting not though... Notebooks are FAR, FAR more power effecient. My 1.2GHz PIII Notebook with 10+" screen is only using up 19watts normally, and up to 32watts at moments with intensive processing or harddrive reads.
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  16. Re:My PSU by Durrik · · Score: 3, Informative

    Sounds like your power supply can't handle the inrush current for the start up of your hard drives and fans.

    When motors start up they have to get over the standing still friction of the unit before they get over the hump of startup and then into the lower friction of a moving unit. I would put in a nice graph but slashdot won't let me.

    What the graph looks like is there's a rise up to a peak. Doing an integration under the line to the peak gives you the force needed to get to the peak. This is the force needed to get to the object moving. The graph then falls down a fair ways, (maybe almost to zero it depends on the two materials being being rubbed together), and then the line stays steady, horizontally. This represents the force needed to keep the object moving.

    This is about all I remember from College physics on friction. There's also some other things that require a high inrush current during startup. But motors are the biggest thing.

    So when you rock your power switch just right you leave the motors running enough not to require the inrush current. Shut off power to the motherboard to force it to restart, but you don't leave the power off long enough to cause the power supply to go into suspend mode and turn off all the power to the system.

    Probably the best thing to do is get a power supply that handles a larger inrush current then the current one. But there could be something else wrong with the system too, and I haven't built a system for close to 8 years and my knowledge might be a bit dated.

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  17. Bad power supply tests by Animats · · Score: 4, Informative
    That article was very lightweight. They didn't do tests that any competent QA shop would do.

    Tests they didn't do, and should have:

    • Look up the UL certification for the unit, and check that the unit actually passed UL testing. Many power supplies, especially from China, have forged UL certifications. (UL had about 80 shipments seized at U.S. Customs last year for this.) UL's test include surviving a dead short and not catching fire for any single component failure. Uncertified power supplies are almost always the ones that catch fire.

      Checking the UL database is easy. Check any power supplies you have, and if the E-number isn't in the database or doesn't match the unit, report it to UL and have a serious talk with the seller.

    • Test the power supply with input voltages at the bottom and top of the rated range, and measure the regulated outputs. This is basic stuff.
    • Test the power supply in a hot box, with temperature maintained at the high end of the specified temperature range. This should be done with the unit loaded up to its rated load, and should continue for at least 72 hours. This, again, is a basic QA test.
    Those are all basic. The "memory test" was interesting. That's an indication that these power supplies differ in their ability to sink RF noise coming in on the power rails. That, too, needs to be tested.

    Nothing Anandtech did seemed to use a 'scope, let alone a spectrum analyzer.

  18. Think carefully about paying more. by Futurepower(R) · · Score: 2, Informative


    More and more companies are basing their business plans on taking advantage of the overclocker, gamer, case modder, or PC enthusiast who doesn't have much technical knowledge. These have slick sales literature and fancy graphics. They also may have no one at the company who knows or cares about the technical details of the product. I feel qualified to say this because, back when I was an electrical engineer, I have designed power supplies and industrial power control devices.

    "Monster cables" won't give you better audio than cheap wire of the same gauge. Similarly, paying a lot of money for a power supply is very unlikely to get you any difference in computer performance, provided you buy a quality low-cost supply.

    We pay $26 wholesale for our 350 Watt KingWin Kwi-350W power supplies, and they are fine. Froogle.google.com says they can be bought retail for $32. The AnandTech article discusses the Kingwin KWI-450, which they say costs $95. Why didn't they review the supply from Kingwin that is 1/3 the cost?

    One guess is that the entire AnandTech article is a hidden Directron.com advertisement. Maybe Directron.com does not want you to know that you don't need to pay more, and that you will derive no benefit from giving Directron more profit.

    The AnandTech article says, "Directron.com let us pick one of every new power supply off their shelves in order to put together a sample of 18 of the newer power supplies on the market right now."

    The article says about the Kingwin KWI-450WABK, "We received our quad fan Kingwin supply well before the TTGI units had hit American soil. The unit was well received in the lab, but as we noticed when the TTGI units arrived, practically identical in construction. TTGI and Kingwin obtain their components from the same manufacturers in Taiwan."

    "Practically identical" does NOT mean identical. Directron's 350 Watt TTGI TT-350SS is $28.99. It looks a lot like the KingWin 350 Watt supply, but is different; the TTGI supply does not have most of the labels that are on the KingWin supply, for example.

    Look below at that link for what Directron says about their warranty: "Customer is responsible for returning defective products including DOA due to manufacturer unless testing is paid before shipping." DOA means "Dead on Arrival". Very clearly, Directron says that they do NOT stand behind their products.

    Directron's warranty may be translated as, "If what we ship you doesn't work, tough luck, don't bother mentioning it to Directron, you are on your own, complain to the manufacturer, and pay the shipping costs to where the manufacturer is located, but we won't tell you in advance where that is, because you might buy directly from the manufacturer." Only if you pay more will Directron stand behind what they ship. So the true cost is not $28.99, unless you want to take your chances.

    I suspect, and I have plenty of evidence, that when companies ask you to pay more for testing if you want a warranty from them, you get absolutely no testing. What you get is only the right to return a DOA unit to them.

    Notice something else about that Directron page. The price is an image, not text, from a different server, yimg.com. Does anyone know why they do that? I don't.

    There is plenty of evidence that the people at AnandTech have little technical understanding. Maybe the site makes money by doing things their advertisers want, which may be different from what is good for you.

    The first page of the AnandTech article says, "We then ran several exhaustive tests on these pow