This looks like an ambitious effort with lots of good test gear, but the thermal and acoustic aspects of the testing setup are seriously flawed.
1) A 1 meter cube box is a *horrific* acoustic test environment. It's way too small to avoid boundary effects. All the acoustic stuffing in the world will not help. You can see in the photo that the mic has to be at one corner and the PSU in the other corner to have 1m distance. Ever stand in the corner to sing? Notice what happens to your voice?
The box will impose its very significant acoustic signature on everything they measure or record in there. The most important effect will be boosts in all the freq below ~500Hz, along with peaks in certain bass frequencies. Any fan used in any PSU will excite such resonances.
Also, there's no indication of what ambient noise level you're getting in there with the Chroma testers going. You mentioned 15 dBA -- I say no way, not with the Chroma machines going. I actually bought a similar AC source device a few years ago and had to abandon it due to the noise problem -- it easily reached 60 dBA @1m. For their test box to achieve 15 dBA ambient with the Chroma machines going in the same room, the box would have to have something like >35 dBA noise isolation and/or the room would have to be gigantic (so that the Chroma machines could be far away.... which then brings up the problem of cable resistance). The former requires astonishing acoustic technology and knowhow; judging by the box construction details, I question whether you can get anywhere near that kind of noise isolation, and if the test room was that big, you'd have said so.
2) The PSU will be in the 1m test box more or less by itself. The box will be sealed during testing. This is unrealistic for 2 reasons --
A) a PSU in a real PC always see some fresh air intake, and
B) it also sees at least some of the heat produced by the components it is feeding.
To expand on this further, the DC output of the PSU goes to components that heat up. These components are in the same case as the PSU, and they affect the ambient temperature of the PSU. It's a simple fact that the total heat generated in the computer is equal to its AC power consumption. Case fans obviously affect the overall thermal situation for the PSU, but the PSU's cooling fan draws air from inside the case. Unless the PSU is in a separate chamber with its own intake vent, it has to deal with not only the heat generated within itself as a result of AC/DC conversion losses, but also at least some of the heat from the components it powers. Heat can affect a PSU's max power output capacity, its stability, and of course, its fan speed/noise.
It's because Anandtech is trying to do "serious" acoustic testing that all this becomes important. In http://www.silentpcreview.com/article683-page1.htm...">SPCR's PSU testing, we have a very clear operational model: The test rig is a close facsimile of a quiet enthusiast's low airflow, low airflow-impedance system. Your test setup doesn't resemble any real system -- there is no fresh air intake, and the exhaust heat goes nowhere. Can such a test setup tell anything practical and worthwhile about the noise/load or the heat/load behavior of any PSU? Certainly not if you intend to install that PSU in a case where there are case fans, intake vents, and other components that also get hot.
I also see another serious thermal issue: It seems to me that in your setup, once a certain amount of heat has been generated inside, continued testing can only lead to continually rising temperature for any PSU. In other words, the temperature/load relationship will be dictated almost entirely by how LONG the PSU is kept running. The heat is trapped in the box; it has nowhere to go, and the box is well insulated. Even at a modest 100W load, leave it running in that test box for a few hours, and I'd bet $$ almost any PSU will shut down due to overheating. So where in the rising curve (over time) could you say is the right point to look at temperature or fan speed or noise? This is a challenging problem.
This is completely different from SPCR's test rig. We generally try to do all the PSU testing at the same room temperature (20~22C), which we can maintain most of the year -- we don't do PSU testing on hot July and August days. This does not stop the internal temperature of the test rig from reaching upwards of 50C at high power load. Importantly, at almost any load level with almost any PSU, the system does come to an equilibrium where temperature (in and out), fan speed and noise stabilize. This is then the obvious point to stop and take measurements.
Furthermore, in the SPCR test rig, almost any well-built PSU can be run at >75% of rated power indefinitely without overheating, which I think cannot be true of your current setup in that sealed box. (I wanted to say 100%, but I suspect this is not true -- even some of the well-built PSUs may overheat at full load if left at full load long enough.) All this is to say that our test rig has predictable thermal characteristics that do closely resemble a real PC system, which is very important if you want to do accurate acoustic testing / analysis. It's also very important for thermal analysis.
Hey Mike,
You can be sure your concern will be taken into account. First of all the box isn't just 1m. It just looks like this on the pictures but an extension is already planned since we also want to fit chassis inside. The PSU and Mic have enough room to the sides and yes, we separated the Chroma and the PSU that much from each other that we can test just fine. As said currently we are still working on the audio part but the box like it is brought us far until now.
We will have both room-temp and 50°C from the next review on since we think it is important to show what a PSU can handle. We don't know where the PSU is running later thus we present as many results possible that our readers have enough information to form an own opinion.
Could you test what happens to the power supply when there's a sudden drop in voltage and then a surge back to normal? I figure that'd emulate someone turning on, say, a heater on the same circuit?
Now, I know a lot of people will say only an idiot would ever plug a computer with other appliance that have high power draw...well...sometimes we have to build computers for people who are a bit, how should we say, technically challenged. WOuld be nice to know if there are any foolproof PSU's for those situations.
The way in which a power supply acts at power-up and power-down can be very important. These guys publish specifications for PS's that include timing specifications for this.
I need power supplies that "boot up" and shut down cleanly, in order to test my company's products to see that they meet spec for their own behavior at power-up and power-down time. Some power supplies that have been highly rated in the press have ugly ramp-up voltage waveforms that make it impossible for me to make measurements on our PCI-X and PCI-E boards.
I have seen how bad things can happen on a PCI bus if power-up doesn't go right, most commonly failure for devices to properly initialize and enumerate on the bus.
In the case of the "bad" power supplies I got, it was easy to see with an oscilloscope that the voltage did not ramp up cleanly, and it wasn't even necessary to know the official specs to see that something was wrong. I think that simply capturing a trace showing all the voltages ramp up and ramp down should be able to weed out the worst offending power supplies.
I'm no expert on these things, but I can see that PSUs would be a very difficult component to test in a meaningful way, and though there are a few things your setup appears to overlook, you've done an awesome job of putting together a rig that can do it as well as can reasonably be expected (once you get the ripple measurements figured out). Must have cost a bundle, but there's little doubt that this will make AT the world's #1 source for PSU info. And that anechoic chamber/box/whatever will come in handy for getting accurate SPL measurements from a whole bunch of other stuff, too! I just hope a PSU doesn't decide to explode or catch fire inside your nifty box and ruin it...
Also, I assume you'll only be using the box for relatively quick sound measurements and not for the actual load testing. If not, how will you deal with the rapidly and indefinitely - till something fails - rising temps inside the extremely well insulated box? I mean, hooray for stress testing, but wouldn't that get a little extreme?
Either way, props on doing it right or not at all.
You should add a few additional temps to determine the robustness of the power supply.
First:
Check stable outputs during different levels of short and long term power brown outs and surges. (handles 1 sec at 250V things like that.
Second:
check stability as temp gets out of control.
Raise the ambient temp to see if the output changes as the temp increases. Power supplies tend to suck air from the case so it could see cool-side temps up to 50C
quote: For example, we may see a few PSUs that perform extremely well, provided you don't exceed certain loads on some of the voltage rails.
Good point. Just because a certain digital camera fails when it is submerged underwater, it doesn't mean all users should stick to only buying waterproof cameras. You'd still have a great camera, provided you keep it out of the water.
<quote>The ambient temperature around the power supply will constantly grow with the time of the test. It will be placed in the same set of conditions it will experience in a real system, where the temperature rises over time.</quote>
I'm very glad to see this highlighted in your review strategy.
It always irks me when I see temperature scores of heatsinks which don't consider the variable temperature of the cooling substance (the air) that was used!
If you blow hot 90 degree air over something, the best it can do is cool that something to 90 degrees. If you blast a heatsink with cool compressed air, you'd get much lower heatsink temperatures.
About that 5 layer box...
I re-read that page a couple times but don't get it. How do you connect the PS unit to the programmable load without running a cable through the wall of the box? If I'm reading it right, you are using the internal PCB to reduce the # of cables you run through the wall to a single cable...?
I'm just curious as it wasn't immediatly clear what was going on there.
Otherwise I applaud you for the new branch of quality reviews you're starting. I look forward to the first review!
quote: To test the quality of the DC output we need an oscilloscope as well. This is important since each output has certain ripple and noise levels, and these are different with each power supply - even those from the same manufacturer. The ripple and noise are leftovers from the electric pulse, and every power supply should implement certain measures to reduce the ripple to an acceptable grade. The actual Power Supply Design Guide specifies that each +12V rail should not have any ripple over 120mV and the +3.3V and +5V rails should not have any ripple over ~50mV. Unfortunately we cannot present these tests right away since we are still working on the best methods. We will conduct those measurements soon and include them in the reviews.
I would urge you not to start doing PSU reviews until you have got the measurement of ripple figured out. It's one of the most important measures of PSU performance, IMNSHO.
I second that. Measuring ripple on my scope under various loads is the first thing I do when I get a new PSU. I have an old surplus Tektronix I use. I would not be interested in any reviews that don't include ripple measurements -- it would be useless.
But Thank You, THANK YOU for finally doing serious PSU tests. The sites that do fluff pieces about the latest shiny boxes have always irritated me no end!
HardOCP pretty much is the gold standard on real, tough, power supply reviews atm. It will be interesting to see if you get the same results as they do.
One thing that happens all the time in the HardOCP reviews is that a PSU will work great up to about 75% of its rating, then fail or get out of spec. My question is... will you consider that a failure or will you just recommend the PSU as long as you don't go over 75% ? No one runs a PSU fully loaded on purpose anyways.
One more thing slightly off topic... how come Anand (and everyone else in the biz) is willing to load a PSU to the max but won't review a motherboard loaded with the maximum "supported" memory? The latter is a much bigger problem imo, and with 64 bit OSes now commonplace that can make use of all the memory in a computer, the time is right to start reviewing MBs that supposedly support 8 GB of ram... while actually loaded with 8 GB of ram.
I recently bought some motherboards to build desktop systems for some of our grad students. They claim support for 16GB RAM, but since they only have 2 slots for RAM testing 16GB falls somewhere between "extremely expensive" and "impossible".
I would like to see that as well. MB's performance with a full load of RAM. (Actually I would want to know if there are any other issues when you run it like that.)
On the Temperature page where it says "We will start at a room temperature of 77°F (25°C)" perhaps mention should be made that the "room" is actually a sealed box, which appears to have far less air volume (and circulation) than the average room, so the air will get far warmer than it ever should in an actual case.
For the most accurate sound level testing, the air temperature around the microphone and the power supply is very VERY important. The microphone must reach steady state temperature and be calibrated at that temperature. The air temperature in the anechoic chamber must be maintained as constant, otherwise the microphone measurements will be off as much as 3-4dB in my experience for a temp delta of only 15°F.
Also, no one is interested in the noise PS generates inside the PC case, rather the noise emitted to the exterior of the PC. And beware the air temperature inside the PC is much much higher than the interior PC air temperature. I don't see how your test approach will address these critical issues.
Thanks, looking forward for the reviews. Please don't let it delay (or MIA) like those m-atx or motherboard.
It will be more interesting than all those HSF reviews...
quote: In most parts of the world it is usual to use a grid power of 230VAC with a frequency of 50Hz. In the US, Canada, and parts of South America however the standards are around 117VAC with a frequency of 60Hz (commonly rounded to 120VAC).
A small nitpick... Japan is also 120VAC (actually 100) and uses flat blade plugs. I live in Japan and everthing I brought here from the US works fine. See
http://www.kropla.com/electric2.htm
I used to test power sources and signal sources for variaous automotive components, and I am wondering why you are using a multimeter to measure the output instead of an oscilliscope. You can measure both current and voltage and actually capture the waveform to measure the ripple voltage with a good o-scope. When it comes to analyzing signals, the oscilliscope is a far more valuable tool than a multimeter.
I'm interested in how the power supply handles electrical noise from the power company. I know most of us have battery backups, but the power supply should do power line noise suppression too. In my area we have brownouts (low voltage), spikes (lightning strikes nearby), and just general noise. I also use computers in a manufacturing environment, which causes significant noise on the power lines.
What you want then, are line conditioners, or a UPS with line-conditioning capability.
The most a power supply provides is Active Power Factor Correction, which will clean up things a little, but that's not a subsitute for a UPS with line conditioning, which will solve your issues with brownouts and spikes. This kind of gear would be expensive and bulky to try and add into a power supply; I don't see it happening any time soon.
I've used a kill a watt device to test for pfc, seems most computers are around 0.6 to 0.64. My old Shuttle box with a replaced power supply with active pfc gets a 0.95 pfc.
This is an excellent commitment to a quality review methodology which will not only benefit the Anandtech community, but the whole power supply industry if the message here is taken to heart by consumers. That anandtech has decided to actively create a reliable and consistent power supply review rig is just another example of exactly why I have come to this great site for so many years.
How fast can you ramp the current on that rig? I'd be very interested to see how PSUs respond to sudden changes in power usage (caused by sudden changes in CPU/GPU load, HDDs spinning up/down, etc).
Even if the fancy equipment can't handle it, measuring this shouldn't be too hard with a cheap digital scope and a 20W passive load. Put the probe on the 12V rail to be measured, attach one end of the load to ground, attach the trigger to the high side of the load, then connect the high side of the load to the 12V rail. Should give a nice edge to trigger on. The trick would be connecting the high side fast enough. A switch/relay would probably be too slow, though a bank of MOSFETS should do the job fine. Actually, the current to turn on the MOSFET bank itself would be a good transient test :)
Also, I think a far more interesting thing with respect to temperature is how the PSU reacts to elevated temperatures, as opposed to temperature WRT load. Since a lot of cheaper PSUs are rated at 20 deg C, I'd expect to see them struggling to supply full power at 40 deg C or so. You'd need to regulate the intake air temperature, but that shouldn't be too hard.
quote: Chroma Programmable AC Power Source 61600 Series use DSP technology to program voltage waveform. Users can change the voltage or
frequency in only one step. Or users can set the slew rate to get a gradual increase or decrease of voltage and frequency. It can help users
easily to test the power input range of their products, for example, 90V-264V/47Hz-63Hz.
That's the "mains" supply thing. I noticed that you can read the module number in one of the shots, and it appears that the 63103 can do dynamic load tests - 5 A/us slew with adjustable repetition rates should do the job nicely. I'd be really, really interested to see some results from this.
Great looking setup. (I love the sound isolating box). I Finally feel like I'll actually learn something from a power supply review.
I agree with BladeVenom, I really hope to see some midrange/budget PSUs as well as the higher end ones.
One other thing that would be nice to see in reviews (not just the power supply ones), is longer term reliability. Most things (and especially computer components), aren't really built with longevity in mind, and with certain critical components (power supplies, hard drives, etc) it would be nice to know if certain companies build longer lasting products than others. I understand the difficulties involved with something like that, so I don't really expect to see it, but it would be nice.
I'm not sure midrange or budget power supplies are ever a great idea, unless they are just low power units. A couple of times I bought cases with these power supplies, and was just plopping an old motherboard in it so I didn't care too much, and found they are really problematic. They poison everything downstream from them, which is pretty much everything, and they do nothing good for the reliability of the system, and of course greatly reduce the lifespan of it.
The one part of system that should never be compromised on is the power supply. A slower processor or video card might work fine for most people, and if it's not fast enough, it's not catastrophic. A poorly made power supply can have catastrophic consequences and whatever money you save on it, it can cost you later on in multiples of it. You can't make a good power supply out of bad components either, so I don't see how a low cost power supply could impress. Even if it did fairly well in their tests, I'd have serious concerns about the reliability and what will happen to it as time goes along. Low cost power supplies can't be using the same high quality parts, after all.
I'm not knocking power supplies that cost a little because they have relatively low power output. I'm saying if you see an 800 watt power supply that is costing 40% less that other quality 800 watt power supplies with the same feature set, you're asking for trouble buying it. You don't roll dice with power supplies.
Still, it might be interesting just to see the differences quantified, between low and high quality power supplies. I just hope it doesn't lead to people buying the low quality junk. That would be a terrible disservice. It's better to save money on ANY other part of the system before the power supply.
When I think of midrange PSUs, I think of lower wattage models (380-450) by reputable vendors. However, as the article mentions, there are a lot of new players popping up in this market. Hopefully that kind of competition is leading to more competative pricing. It may cease to be true that you need to spend over $100 to get a high quality PSU.
My point is that there may be some real value to testing less expensive PSUs.
I get the impression from this article that AT will test a wide range of PSUs (from a wattage standpoint). I hope that is the case. There is nothing more frustrating to me than finding reputable review sites who don't have any recomended PSUs below the 700 watt level.
I had a Antec NeoPower PSU spew black smoke. It was not fun. Also fried my motherboard. It was less than 6 months old too, and I wasn't using it at anywhere near it's supposed capacity.
quote: The bottom line is, a normal PC is just not enough to fully load a high-end power supply, and therefore it cannot be properly tested and surely not approved by such a configuration.
Then test power supplies that are in the range that most people actually need. Also test some budget ones. Let's see which ones are good for the money, and which ones are fire hazards.
what is meant is that the idea of having a psu is NOT to load it to 100% capacity.
and the problem being that it is very difficult to get a stable and repeatable psu testing setup.
I highly recommend that industrial manufacturers be pointed out just like in xbit labs reviews. That way we will know that antec has 3 or more suppliers providing psu's and be able to tell the seasonics from the other crud ;)
hmm i wonder if thats why some people rave about Antec and some people like me curse them! I'd have to say Antec have the worst failure rate by far, probably at about 75% in the first year, where i can buy a $22 550W Generic (Honli) and only have about a 25% failure rate, maybe thats related to the power supplys released into australia by antec.
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tynopik - Tuesday, July 17, 2007 - link
please please please add brownout/sag/powerdip/flicker tests!this is a big killer of power supplies and personally caused one of mine to blow up and take out everything connected to it (mb, 3 hd, cd, etc)
test how it maintains power when the voltage drops down to 90v
test how it responds to a series of flickers (this is what killed mine)
gold standards in PSU review
jonnyguru.com
silentpcreview.com
mcvan - Friday, July 13, 2007 - link
This looks like an ambitious effort with lots of good test gear, but the thermal and acoustic aspects of the testing setup are seriously flawed.1) A 1 meter cube box is a *horrific* acoustic test environment. It's way too small to avoid boundary effects. All the acoustic stuffing in the world will not help. You can see in the photo that the mic has to be at one corner and the PSU in the other corner to have 1m distance. Ever stand in the corner to sing? Notice what happens to your voice?
The box will impose its very significant acoustic signature on everything they measure or record in there. The most important effect will be boosts in all the freq below ~500Hz, along with peaks in certain bass frequencies. Any fan used in any PSU will excite such resonances.
Also, there's no indication of what ambient noise level you're getting in there with the Chroma testers going. You mentioned 15 dBA -- I say no way, not with the Chroma machines going. I actually bought a similar AC source device a few years ago and had to abandon it due to the noise problem -- it easily reached 60 dBA @1m. For their test box to achieve 15 dBA ambient with the Chroma machines going in the same room, the box would have to have something like >35 dBA noise isolation and/or the room would have to be gigantic (so that the Chroma machines could be far away.... which then brings up the problem of cable resistance). The former requires astonishing acoustic technology and knowhow; judging by the box construction details, I question whether you can get anywhere near that kind of noise isolation, and if the test room was that big, you'd have said so.
2) The PSU will be in the 1m test box more or less by itself. The box will be sealed during testing. This is unrealistic for 2 reasons --
A) a PSU in a real PC always see some fresh air intake, and
B) it also sees at least some of the heat produced by the components it is feeding.
To expand on this further, the DC output of the PSU goes to components that heat up. These components are in the same case as the PSU, and they affect the ambient temperature of the PSU. It's a simple fact that the total heat generated in the computer is equal to its AC power consumption. Case fans obviously affect the overall thermal situation for the PSU, but the PSU's cooling fan draws air from inside the case. Unless the PSU is in a separate chamber with its own intake vent, it has to deal with not only the heat generated within itself as a result of AC/DC conversion losses, but also at least some of the heat from the components it powers. Heat can affect a PSU's max power output capacity, its stability, and of course, its fan speed/noise.
It's because Anandtech is trying to do "serious" acoustic testing that all this becomes important. In http://www.silentpcreview.com/article683-page1.htm...">SPCR's PSU testing, we have a very clear operational model: The test rig is a close facsimile of a quiet enthusiast's low airflow, low airflow-impedance system. Your test setup doesn't resemble any real system -- there is no fresh air intake, and the exhaust heat goes nowhere. Can such a test setup tell anything practical and worthwhile about the noise/load or the heat/load behavior of any PSU? Certainly not if you intend to install that PSU in a case where there are case fans, intake vents, and other components that also get hot.
I also see another serious thermal issue: It seems to me that in your setup, once a certain amount of heat has been generated inside, continued testing can only lead to continually rising temperature for any PSU. In other words, the temperature/load relationship will be dictated almost entirely by how LONG the PSU is kept running. The heat is trapped in the box; it has nowhere to go, and the box is well insulated. Even at a modest 100W load, leave it running in that test box for a few hours, and I'd bet $$ almost any PSU will shut down due to overheating. So where in the rising curve (over time) could you say is the right point to look at temperature or fan speed or noise? This is a challenging problem.
This is completely different from SPCR's test rig. We generally try to do all the PSU testing at the same room temperature (20~22C), which we can maintain most of the year -- we don't do PSU testing on hot July and August days. This does not stop the internal temperature of the test rig from reaching upwards of 50C at high power load. Importantly, at almost any load level with almost any PSU, the system does come to an equilibrium where temperature (in and out), fan speed and noise stabilize. This is then the obvious point to stop and take measurements.
Furthermore, in the SPCR test rig, almost any well-built PSU can be run at >75% of rated power indefinitely without overheating, which I think cannot be true of your current setup in that sealed box. (I wanted to say 100%, but I suspect this is not true -- even some of the well-built PSUs may overheat at full load if left at full load long enough.) All this is to say that our test rig has predictable thermal characteristics that do closely resemble a real PC system, which is very important if you want to do accurate acoustic testing / analysis. It's also very important for thermal analysis.
Christoph Katzer - Monday, July 16, 2007 - link
Hey Mike,You can be sure your concern will be taken into account. First of all the box isn't just 1m. It just looks like this on the pictures but an extension is already planned since we also want to fit chassis inside. The PSU and Mic have enough room to the sides and yes, we separated the Chroma and the PSU that much from each other that we can test just fine. As said currently we are still working on the audio part but the box like it is brought us far until now.
We will have both room-temp and 50°C from the next review on since we think it is important to show what a PSU can handle. We don't know where the PSU is running later thus we present as many results possible that our readers have enough information to form an own opinion.
Christoph Katzer - Friday, July 13, 2007 - link
Thanks for all your comments and suggestions. You can be sure that it will all be taken into account and we are working on it right now.giantpandaman2 - Friday, July 13, 2007 - link
Could you test what happens to the power supply when there's a sudden drop in voltage and then a surge back to normal? I figure that'd emulate someone turning on, say, a heater on the same circuit?Now, I know a lot of people will say only an idiot would ever plug a computer with other appliance that have high power draw...well...sometimes we have to build computers for people who are a bit, how should we say, technically challenged. WOuld be nice to know if there are any foolproof PSU's for those situations.
langenbacher - Thursday, July 12, 2007 - link
The way in which a power supply acts at power-up and power-down can be very important. These guys publish specifications for PS's that include timing specifications for this.http://ssiforum.org">http://ssiforum.org http://ssiforum.org/specifications.aspx#powerSuppl...">http://ssiforum.org/specifications.aspx#powerSuppl...
http://www.formfactors.org">http://www.formfactors.org http://www.formfactors.org/developer%5Cspecs%5CPSU...">http://www.formfactors.org/developer%5Cspecs%5CPSU...
I need power supplies that "boot up" and shut down cleanly, in order to test my company's products to see that they meet spec for their own behavior at power-up and power-down time. Some power supplies that have been highly rated in the press have ugly ramp-up voltage waveforms that make it impossible for me to make measurements on our PCI-X and PCI-E boards.
I have seen how bad things can happen on a PCI bus if power-up doesn't go right, most commonly failure for devices to properly initialize and enumerate on the bus.
In the case of the "bad" power supplies I got, it was easy to see with an oscilloscope that the voltage did not ramp up cleanly, and it wasn't even necessary to know the official specs to see that something was wrong. I think that simply capturing a trace showing all the voltages ramp up and ramp down should be able to weed out the worst offending power supplies.
erikpurne - Thursday, July 12, 2007 - link
I'm no expert on these things, but I can see that PSUs would be a very difficult component to test in a meaningful way, and though there are a few things your setup appears to overlook, you've done an awesome job of putting together a rig that can do it as well as can reasonably be expected (once you get the ripple measurements figured out). Must have cost a bundle, but there's little doubt that this will make AT the world's #1 source for PSU info. And that anechoic chamber/box/whatever will come in handy for getting accurate SPL measurements from a whole bunch of other stuff, too! I just hope a PSU doesn't decide to explode or catch fire inside your nifty box and ruin it...Also, I assume you'll only be using the box for relatively quick sound measurements and not for the actual load testing. If not, how will you deal with the rapidly and indefinitely - till something fails - rising temps inside the extremely well insulated box? I mean, hooray for stress testing, but wouldn't that get a little extreme?
Either way, props on doing it right or not at all.
erikejw - Thursday, July 12, 2007 - link
"To measure the produced noise we have build an anechoic room in which we can measure the noise down to just 15 dB(A)."Please use this when you test fans too, it would rock.
Looking forward to this series of tests too.
Conky - Thursday, July 12, 2007 - link
This is long overdue. No more relying on lesser sites for PSU info. :)markitect - Thursday, July 12, 2007 - link
You should add a few additional temps to determine the robustness of the power supply.First:
Check stable outputs during different levels of short and long term power brown outs and surges. (handles 1 sec at 250V things like that.
Second:
check stability as temp gets out of control.
Raise the ambient temp to see if the output changes as the temp increases. Power supplies tend to suck air from the case so it could see cool-side temps up to 50C
crimson117 - Thursday, July 12, 2007 - link
Good point. Just because a certain digital camera fails when it is submerged underwater, it doesn't mean all users should stick to only buying waterproof cameras. You'd still have a great camera, provided you keep it out of the water.
crimson117 - Thursday, July 12, 2007 - link
<quote>The ambient temperature around the power supply will constantly grow with the time of the test. It will be placed in the same set of conditions it will experience in a real system, where the temperature rises over time.</quote>I'm very glad to see this highlighted in your review strategy.
It always irks me when I see temperature scores of heatsinks which don't consider the variable temperature of the cooling substance (the air) that was used!
If you blow hot 90 degree air over something, the best it can do is cool that something to 90 degrees. If you blast a heatsink with cool compressed air, you'd get much lower heatsink temperatures.
Rocket321 - Thursday, July 12, 2007 - link
About that 5 layer box...I re-read that page a couple times but don't get it. How do you connect the PS unit to the programmable load without running a cable through the wall of the box? If I'm reading it right, you are using the internal PCB to reduce the # of cables you run through the wall to a single cable...?
I'm just curious as it wasn't immediatly clear what was going on there.
Otherwise I applaud you for the new branch of quality reviews you're starting. I look forward to the first review!
nrb - Thursday, July 12, 2007 - link
I'm slightly concerned by this statement: I would urge you not to start doing PSU reviews until you have got the measurement of ripple figured out. It's one of the most important measures of PSU performance, IMNSHO.kaborka - Saturday, July 14, 2007 - link
I second that. Measuring ripple on my scope under various loads is the first thing I do when I get a new PSU. I have an old surplus Tektronix I use. I would not be interested in any reviews that don't include ripple measurements -- it would be useless.But Thank You, THANK YOU for finally doing serious PSU tests. The sites that do fluff pieces about the latest shiny boxes have always irritated me no end!
EODetroit - Thursday, July 12, 2007 - link
HardOCP pretty much is the gold standard on real, tough, power supply reviews atm. It will be interesting to see if you get the same results as they do.One thing that happens all the time in the HardOCP reviews is that a PSU will work great up to about 75% of its rating, then fail or get out of spec. My question is... will you consider that a failure or will you just recommend the PSU as long as you don't go over 75% ? No one runs a PSU fully loaded on purpose anyways.
One more thing slightly off topic... how come Anand (and everyone else in the biz) is willing to load a PSU to the max but won't review a motherboard loaded with the maximum "supported" memory? The latter is a much bigger problem imo, and with 64 bit OSes now commonplace that can make use of all the memory in a computer, the time is right to start reviewing MBs that supposedly support 8 GB of ram... while actually loaded with 8 GB of ram.
CrystalBay - Thursday, July 12, 2007 - link
So how is PCP&C's 750 Silencer gonna stack up with it's 80mm fan???End The Power Supply Myths AT........
strikeback03 - Thursday, July 12, 2007 - link
I recently bought some motherboards to build desktop systems for some of our grad students. They claim support for 16GB RAM, but since they only have 2 slots for RAM testing 16GB falls somewhere between "extremely expensive" and "impossible".Martimus - Thursday, July 12, 2007 - link
I would like to see that as well. MB's performance with a full load of RAM. (Actually I would want to know if there are any other issues when you run it like that.)strikeback03 - Thursday, July 12, 2007 - link
Nice new toys:)On the Temperature page where it says "We will start at a room temperature of 77°F (25°C)" perhaps mention should be made that the "room" is actually a sealed box, which appears to have far less air volume (and circulation) than the average room, so the air will get far warmer than it ever should in an actual case.
jtleon - Thursday, July 12, 2007 - link
For the most accurate sound level testing, the air temperature around the microphone and the power supply is very VERY important. The microphone must reach steady state temperature and be calibrated at that temperature. The air temperature in the anechoic chamber must be maintained as constant, otherwise the microphone measurements will be off as much as 3-4dB in my experience for a temp delta of only 15°F.Also, no one is interested in the noise PS generates inside the PC case, rather the noise emitted to the exterior of the PC. And beware the air temperature inside the PC is much much higher than the interior PC air temperature. I don't see how your test approach will address these critical issues.
jtleon - Thursday, July 12, 2007 - link
Ooops...I meant to say,And beware the air temperature inside the PC is much much higher than the exterior PC air temperature.
LTG - Thursday, July 12, 2007 - link
This is exactly the high bar I expected from AT and I'm really glad to see you guys do it right.I've always felt that other review sites were missing a lot in this area.
LTG
lsman - Thursday, July 12, 2007 - link
Thanks, looking forward for the reviews. Please don't let it delay (or MIA) like those m-atx or motherboard.It will be more interesting than all those HSF reviews...
Kensei - Thursday, July 12, 2007 - link
A small nitpick... Japan is also 120VAC (actually 100) and uses flat blade plugs. I live in Japan and everthing I brought here from the US works fine. See
http://www.kropla.com/electric2.htm
Martimus - Thursday, July 12, 2007 - link
I used to test power sources and signal sources for variaous automotive components, and I am wondering why you are using a multimeter to measure the output instead of an oscilliscope. You can measure both current and voltage and actually capture the waveform to measure the ripple voltage with a good o-scope. When it comes to analyzing signals, the oscilliscope is a far more valuable tool than a multimeter.just my 2 cents.
acronos - Thursday, July 12, 2007 - link
I'm interested in how the power supply handles electrical noise from the power company. I know most of us have battery backups, but the power supply should do power line noise suppression too. In my area we have brownouts (low voltage), spikes (lightning strikes nearby), and just general noise. I also use computers in a manufacturing environment, which causes significant noise on the power lines.LoneWolf15 - Thursday, July 12, 2007 - link
What you want then, are line conditioners, or a UPS with line-conditioning capability.The most a power supply provides is Active Power Factor Correction, which will clean up things a little, but that's not a subsitute for a UPS with line conditioning, which will solve your issues with brownouts and spikes. This kind of gear would be expensive and bulky to try and add into a power supply; I don't see it happening any time soon.
LoneWolf15 - Thursday, July 12, 2007 - link
Clarification: Not every PSU has Active PFC --a better explanation can be found here:http://www.dansdata.com/gz028.htm">http://www.dansdata.com/gz028.htm
sprockkets - Saturday, July 14, 2007 - link
Yeah very good explanation. Another way of looking at it is I found a site sometime ago that showed the pfc as a 90 triangle to show the relationship.I'm looking for a good test of those fanless power supplies, but again, without a fan it does put a damper in the cooling.
sprockkets - Saturday, July 14, 2007 - link
I've used a kill a watt device to test for pfc, seems most computers are around 0.6 to 0.64. My old Shuttle box with a replaced power supply with active pfc gets a 0.95 pfc.Phlargo - Thursday, July 12, 2007 - link
This is an excellent commitment to a quality review methodology which will not only benefit the Anandtech community, but the whole power supply industry if the message here is taken to heart by consumers. That anandtech has decided to actively create a reliable and consistent power supply review rig is just another example of exactly why I have come to this great site for so many years.Great work!
mostlyprudent - Thursday, July 12, 2007 - link
My thoughts exactly!qpwoei - Thursday, July 12, 2007 - link
How fast can you ramp the current on that rig? I'd be very interested to see how PSUs respond to sudden changes in power usage (caused by sudden changes in CPU/GPU load, HDDs spinning up/down, etc).Even if the fancy equipment can't handle it, measuring this shouldn't be too hard with a cheap digital scope and a 20W passive load. Put the probe on the 12V rail to be measured, attach one end of the load to ground, attach the trigger to the high side of the load, then connect the high side of the load to the 12V rail. Should give a nice edge to trigger on. The trick would be connecting the high side fast enough. A switch/relay would probably be too slow, though a bank of MOSFETS should do the job fine. Actually, the current to turn on the MOSFET bank itself would be a good transient test :)
Also, I think a far more interesting thing with respect to temperature is how the PSU reacts to elevated temperatures, as opposed to temperature WRT load. Since a lot of cheaper PSUs are rated at 20 deg C, I'd expect to see them struggling to supply full power at 40 deg C or so. You'd need to regulate the intake air temperature, but that shouldn't be too hard.
JonnyBlaze - Thursday, July 12, 2007 - link
looks like it can do it.
qpwoei - Friday, July 13, 2007 - link
That's the "mains" supply thing. I noticed that you can read the module number in one of the shots, and it appears that the 63103 can do dynamic load tests - 5 A/us slew with adjustable repetition rates should do the job nicely. I'd be really, really interested to see some results from this.ATWindsor - Thursday, July 12, 2007 - link
Hopefully you will be using the box for some other SPL-measurments on equipment that is not a PSU also?AtW
WW2Planes1 - Thursday, July 12, 2007 - link
Great looking setup. (I love the sound isolating box). I Finally feel like I'll actually learn something from a power supply review.I agree with BladeVenom, I really hope to see some midrange/budget PSUs as well as the higher end ones.
One other thing that would be nice to see in reviews (not just the power supply ones), is longer term reliability. Most things (and especially computer components), aren't really built with longevity in mind, and with certain critical components (power supplies, hard drives, etc) it would be nice to know if certain companies build longer lasting products than others. I understand the difficulties involved with something like that, so I don't really expect to see it, but it would be nice.
TA152H - Thursday, July 12, 2007 - link
I'm not sure midrange or budget power supplies are ever a great idea, unless they are just low power units. A couple of times I bought cases with these power supplies, and was just plopping an old motherboard in it so I didn't care too much, and found they are really problematic. They poison everything downstream from them, which is pretty much everything, and they do nothing good for the reliability of the system, and of course greatly reduce the lifespan of it.The one part of system that should never be compromised on is the power supply. A slower processor or video card might work fine for most people, and if it's not fast enough, it's not catastrophic. A poorly made power supply can have catastrophic consequences and whatever money you save on it, it can cost you later on in multiples of it. You can't make a good power supply out of bad components either, so I don't see how a low cost power supply could impress. Even if it did fairly well in their tests, I'd have serious concerns about the reliability and what will happen to it as time goes along. Low cost power supplies can't be using the same high quality parts, after all.
I'm not knocking power supplies that cost a little because they have relatively low power output. I'm saying if you see an 800 watt power supply that is costing 40% less that other quality 800 watt power supplies with the same feature set, you're asking for trouble buying it. You don't roll dice with power supplies.
Still, it might be interesting just to see the differences quantified, between low and high quality power supplies. I just hope it doesn't lead to people buying the low quality junk. That would be a terrible disservice. It's better to save money on ANY other part of the system before the power supply.
mostlyprudent - Thursday, July 12, 2007 - link
When I think of midrange PSUs, I think of lower wattage models (380-450) by reputable vendors. However, as the article mentions, there are a lot of new players popping up in this market. Hopefully that kind of competition is leading to more competative pricing. It may cease to be true that you need to spend over $100 to get a high quality PSU.My point is that there may be some real value to testing less expensive PSUs.
I get the impression from this article that AT will test a wide range of PSUs (from a wattage standpoint). I hope that is the case. There is nothing more frustrating to me than finding reputable review sites who don't have any recomended PSUs below the 700 watt level.
Adul - Thursday, July 12, 2007 - link
I'd love to see a power supply catch fire :). Maybe one of the cheaper ones will break enough for this.CrystalBay - Thursday, July 12, 2007 - link
I would also like to see a short video of substandard PSU's lighting up...I'm sure many enthusiasts have had Dram's start flaming or smoke. But I have never had a PSU actually catch flame out....
Martimus - Thursday, July 12, 2007 - link
I had a Antec NeoPower PSU spew black smoke. It was not fun. Also fried my motherboard. It was less than 6 months old too, and I wasn't using it at anywhere near it's supposed capacity.BladeVenom - Thursday, July 12, 2007 - link
Then test power supplies that are in the range that most people actually need. Also test some budget ones. Let's see which ones are good for the money, and which ones are fire hazards.
xsilver - Thursday, July 12, 2007 - link
what is meant is that the idea of having a psu is NOT to load it to 100% capacity.and the problem being that it is very difficult to get a stable and repeatable psu testing setup.
I highly recommend that industrial manufacturers be pointed out just like in xbit labs reviews. That way we will know that antec has 3 or more suppliers providing psu's and be able to tell the seasonics from the other crud ;)
Wesleyrpg - Thursday, July 12, 2007 - link
hmm i wonder if thats why some people rave about Antec and some people like me curse them! I'd have to say Antec have the worst failure rate by far, probably at about 75% in the first year, where i can buy a $22 550W Generic (Honli) and only have about a 25% failure rate, maybe thats related to the power supplys released into australia by antec.imaheadcase - Thursday, July 12, 2007 - link
I kid! :Pgersson - Thursday, July 12, 2007 - link
just a red 'X'gersson - Thursday, July 12, 2007 - link
nevermind -- working already :-)