Posted by
Hemos
on from the lets'-get-'em-together dept.
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.
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.
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.
-- I hereby place the above post in the public domain.
28 pages? Give me a break.
by
Anonymous Coward
·
· Score: 5, Informative
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.
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.
-- Mea navis aericumbens anguillis abundat
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.
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. }:)
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.
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.
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.
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.
-- Software Engineer & Writer of Military Science Fiction and Fantasy
Blog: petermwright.com
Twitter: WrightPeterM
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.
Slashdot Mirror
I'm thinking that's a UPS. Servers usually have redundant power supplies, not one for multiple machines.
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.
I hereby place the above post in the public domain.
Single-page link.
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.
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.
Mea navis aericumbens anguillis abundat
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.
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. }:)
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.
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.
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.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
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.
Software Engineer & Writer of Military Science Fiction and Fantasy Blog: petermwright.com Twitter: WrightPeterM
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.
-
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.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.
Nothing Anandtech did seemed to use a 'scope, let alone a spectrum analyzer.