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.
The results of the memory tests are amasing. The MTBF is about an hour on some of the power supplys. I'm not sure If I understand the setup but that is appauling. I expect a MTBF of about 100+ years not an hour.
Not quite as amusing as dansdata.com, but...
by
Junior+J.+Junior+III
·
· Score: 5, Interesting
I really liked Anandtech's article. It actually had a lot of information and was fairly thorough -- measuring performance in a variety of ways, including not just output wattages but also noise levels, heat buildup, and cost.
A bit more explaining the basics of what each different voltage rail is for and why x-level of performance is important would have been helpful. Along with some more basic stats, such as how long the power cables actually are -- surely people still build full-tower PCs, don't they?
-- You see? You see? Your stupid minds! Stupid! Stupid!
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
Not wanting to put a downer on things...
by
WIAKywbfatw
·
· Score: 5, Insightful
...but it strikes me that these reviews of PSUs aren't as accurate as they should be. I'm not wanting to run the guys at AnandTech or elsewhere down (because, most of the time, they do a great job) but it strikes me that, when you look at PSUs (as opposed to CPUs, graphics cards or HDDs) then perhaps testing just one sample of each product is flawed.
After all, some of the measurements taken to distinguish good from bad were to the fifth significant figure. It strikes me that if you have to be that precise to differentiate between the winners and the also-rans then you've got to test more than one of each PSU - three would be a minimum, five or more would be better - and average out the test results to give you figures that are more representative of the quality of these products.
After all, not every Zalman ZM400A-APF is going to have a 12V min/max fluctuation of only 0.005V, and not every Enermax EG651P-VE FMA 550W is going to have a fluctuaction of 0.65V. Who knows, perhaps this was just a particularly good Zalman and a particularly bad Enermax? Testing more units means accurate results, which is a good thing.
I appreciate that testing three (or five, or however many) of each PSU means more work - you have to get x many more of each unit, test x many more times, process x much more data before averaging out your results - but, sometimes, I think it's warranted. Without wanting to get down on anyone, I'd like to suggest that, where called for, they try to source more units and test more thoroughly.
And, before people start flaming me for not knowing what I'm talking about, how much work is involved, etc, let me just say that I've run a review lab and I do know what I'm talking about, how much work is involved, etc. It's not a trivial amount but, sometimes, it is worth it.
(No doubt that's just a cue for half a dozen people to tell me where I'm wrong. I welcome objective criticisms but you can keep any childish flames.)
--
"Accept that some days you are the pigeon, and some days you are the statue." - David Brent, Wernham Hogg
Where's the EE beef?
by
AragornCG
·
· Score: 5, Interesting
Great, there are more power supplies, but where are the oscilloscopes? Where is the detailed methodology for testing the cleanliness of the resultant power? They used some "stuff we found in our local university basement" to satisfy "you EE types". Oh, great. LIKE WHAT?
I'll take a smaller review with decent scientific methodologies, thank you very much. There's more to stability of a power supply than "interference testing" which reports an integer number of errors that could be caused by anything... What about the thermal testing... where was it measured? by what, the onboard mainboard thermistor, which is notably unreliable? Which "industry standard Chenming case" was it?
I really, really, really wish that these hardware sites would hire people with a decent understanding of the discipline of science - let alone engineering! - to write reviews. I could make MUCH more informed decisions.
-Ben
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.
Slashdot Mirror
DOH! NOW I know why my home build PC isn't working. I also made the "often made" mistake of forgetting the Power Supply.
I'm glad to know this is a common mistake and not just me being stupid.
An Eye for an Eye will make the whole world blind - Gandhi
The results of the memory tests are amasing. The MTBF is about an hour on some of the power supplys. I'm not sure If I understand the setup but that is appauling. I expect a MTBF of about 100+ years not an hour.
Mouse powered Chips, Open source Processors and Lego
I really liked Anandtech's article. It actually had a lot of information and was fairly thorough -- measuring performance in a variety of ways, including not just output wattages but also noise levels, heat buildup, and cost.
A bit more explaining the basics of what each different voltage rail is for and why x-level of performance is important would have been helpful. Along with some more basic stats, such as how long the power cables actually are -- surely people still build full-tower PCs, don't they?
You see? You see? Your stupid minds! Stupid! Stupid!
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.
...but it strikes me that these reviews of PSUs aren't as accurate as they should be. I'm not wanting to run the guys at AnandTech or elsewhere down (because, most of the time, they do a great job) but it strikes me that, when you look at PSUs (as opposed to CPUs, graphics cards or HDDs) then perhaps testing just one sample of each product is flawed.
After all, some of the measurements taken to distinguish good from bad were to the fifth significant figure. It strikes me that if you have to be that precise to differentiate between the winners and the also-rans then you've got to test more than one of each PSU - three would be a minimum, five or more would be better - and average out the test results to give you figures that are more representative of the quality of these products.
After all, not every Zalman ZM400A-APF is going to have a 12V min/max fluctuation of only 0.005V, and not every Enermax EG651P-VE FMA 550W is going to have a fluctuaction of 0.65V. Who knows, perhaps this was just a particularly good Zalman and a particularly bad Enermax? Testing more units means accurate results, which is a good thing.
I appreciate that testing three (or five, or however many) of each PSU means more work - you have to get x many more of each unit, test x many more times, process x much more data before averaging out your results - but, sometimes, I think it's warranted. Without wanting to get down on anyone, I'd like to suggest that, where called for, they try to source more units and test more thoroughly.
And, before people start flaming me for not knowing what I'm talking about, how much work is involved, etc, let me just say that I've run a review lab and I do know what I'm talking about, how much work is involved, etc. It's not a trivial amount but, sometimes, it is worth it.
(No doubt that's just a cue for half a dozen people to tell me where I'm wrong. I welcome objective criticisms but you can keep any childish flames.)
"Accept that some days you are the pigeon, and some days you are the statue." - David Brent, Wernham Hogg
Great, there are more power supplies, but where are the oscilloscopes? Where is the detailed methodology for testing the cleanliness of the resultant power? They used some "stuff we found in our local university basement" to satisfy "you EE types". Oh, great. LIKE WHAT?
I'll take a smaller review with decent scientific methodologies, thank you very much. There's more to stability of a power supply than "interference testing" which reports an integer number of errors that could be caused by anything... What about the thermal testing... where was it measured? by what, the onboard mainboard thermistor, which is notably unreliable? Which "industry standard Chenming case" was it?
I really, really, really wish that these hardware sites would hire people with a decent understanding of the discipline of science - let alone engineering! - to write reviews. I could make MUCH more informed decisions.
-Ben
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.