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Five Power Supplies Compared
EconolineCrush writes "Tech Report has done up a comparison of five high-end power supplies that looks at actual voltage levels and AC ripple content. The article also takes a look at environmental factors like noise levels and each power supply's impact on system temperatures. Think power supplies with like wattages are created equal? Think again."
http://www.tomshardware.com/howto/20021021/index.h tml
:)
21 power supply tested here
Good PSUs contribute a lot towards system stability. For example, a moving head in the HDD causes current transients (so does a CPU switching between normal operation and power saving mode). Bad PSUs have huge voltage drops during these transients, good PSUs can buffer them quite well. These transients can cause anything between nothing and total system crash.
Also, the ability to filter noise out of the AC helps with stability...
AnandTech also just had a PSU roundup here. The watt numbers and some of that aren't the best from AnandTech's review (read some criticism of it here), but overal it's a good roundup, especially comparing heat and noise.
As the article concludes, Antec is the best option available. I run a server with a 300 watt Antec powering the system, and a separate Antec 400 watt running ten of the eleven hard drives. The voltages stay tight and the supplies stay cool. The 500+ watt models are expensive, but the $69 I paid for the 400 watt is well worth it when you are protecting 1.1TB worth of drives.
:(
On the cheap/lower power side, I've had great success with Sparkle and Enlight (250-350 watt) supplies. Priced in the $22-$40 range, these are great for "normal" systems.
I definitely recommend you stay away from the cheap stuff that comes in $30 cases, though... you'll see why when the supply dies, or shorts taking the mobo with it.
Read this page from AnandTech's PSU roundup. The only thing that was changed between tests was PSUs, yet over a 6 hour time there was a range of only 1 up to 7 memory errors. Just one possible indication of how clean the supply is. Also there's the added benefit that it probably won't die in a month or two (happened to me, not too pleased when it did)
anandtech reviewed 18 units on july 31.
Interesting there is the memory test: they show that stable power gives less memory errors with memtest.
And here is clickable tomshardware:
Toms burns up some power supplies
In a cheap power supply, you can get inconsistent voltages, crazy transients, crosstalk, and if the power demand from one line goes up it can drop the wattage/voltage on the other lines. Cheap power supplies are also frequently noisier (sound too) than high end ones and run less efficiently (read: hot) than better designed, more expensive power supplies. Think about it: your computer operates because of well controlled voltages. If your voltage drops by 2V, some transistors will go into their linear range and cause crazy crazy crap to happen.
See my reply here.
The reason they check the voltages so closely is that one you start falling out of the 5 or maybe 10% tolerance zone for many components, over-voltage will cause overheating, lockups and early failure, and undervoltage also frequently causes lockups and occaisionally failure.
Also, some supplies give you a total wattage without breaking down where those watts can go. When you're dealing with processors that pull 80 watts at peak, you REALLY don't want a cheap supply that is busy sending all available watts to 5 and 12 volt channels to power drives.
Another thing to consider when buying a case.. the PS they put in cases are the CHEAP kind, unless they specify what kind it is, I generally expect to replace it within a year. A few years ago I had one of the dual socket370 BP-6 boards, it refused to boot on the PS I had that came with my case (Enlight none the less). I swapped it to a sparkle 300watt and have had no probs since.
This was also recently covered by Tom's Hardware, and earlier by a few other sites. The sparkle and HEC normally blow away the rest, with their 250w beating the specs for most 300+w, and even being able to hold 300w operation themselves.
just my $.02
Tm
Support TBI Research: http://www.raisinhope.org
If you've got weak voltages on the PSU rails, it can kill your HDDs. Some people lose drive after drive and never consider that their voltages are out of spec. Also, if your cheap PSU shorts on the DC side, say goodbye to your drives and maybe your motherboard and everything plugged into it.
Here .. try this. I think there are 17+ power supplies that they reviewed. All the way from top end to bottom of the barrel in some cases.
power supplies review
-- Knowing too much can get you killed, but knowing who knows too much can make you rich.
Why is it that every time these "high-end" power supplies get compared, the most high-end one always gets ignored? PC Power and Cooling has long manufactured the world's best power supplies. They're the Ferrari or the Moto Guzzi of the power supply world. Yeah, lots of Asian manufacturing firms make OK power supplies, but PCP&C's stuff is the only company that makes boards that the major motherboard manufacturers highly recommend and use exclusively in their own tests. Why does such an obvious high-quality product always get ignored?
Rail wattage is also important because power supplies have 12, 5, and 3.3 volt supply rails. If the 5 and 3.3 are sharing the same rail then you are limited to the wattage from that single rail. Antec was the only power supply to have separate 5 and 3.3 rails. If you don't have enough power going to your components under a heavy load, your system will crash. Think of the power supply like a carburetor. If it's running too lean or you put one 2 barrel carb on a Hemi, it won't run right. If your power supply can't get enough voltage or current out to your components, or you put one on that's too small, your computer won't run right.
Needless to say, I'd buy the Antec. Separate rails for 5 and 3.3 plus the second-lowest ripple make it a good choice for stable power.
Who told you that you should be running your power supplies at close to their maximum load? The guy who was trying to sell you the 200W power supply for a P4? Running at close to the maximum load constnatly will reduce the life of your power supply and make it run hotter.
Also, your surge supressor won't stop normal power spikes, they are only designed to stop grossly over voltage spike like you get with lightning strikes. The worst part is that many of them don't even do that. Did you know that most surge supressors, once they're "blown" will fail into an "on" state. It's amost impossible to check to see if your surge supressor is still working.
I read the internet for the articles.
I'm not a power supply designer, but I do have some experience with system power supplies and their affect on system operation/reliability. If I were deciding upon a power supply for my system (or product), I would carry out the same testing as in the article, but also measure the following four parameters:
1. Initial Power Up overshoot/ringing/stabilization. I would hope the supllies powered up with a basic RC curve "POWERGOOD" becoming active when each of the supplies are within 1% of their targets.
2. Transient response. This is different from the "Load" test, it would look at how the power supply worked when it went from minimum load to maximum load and back again. Say starting up the disk drives, CD-ROM and change the fan speed at the same time.
3. Transient response across supplies. What happens if there is a large transient on another supply. The different power outputs in modern power supplies are not as separate as you might think.
4. Power down characteristics. Again, this should be a smooth RC curve with no overshoots or ringing. The high power positive voltage outputs should never go negative.
The first and last parameters will be an indicator of how "gentle" the power supply is on the components and whether or not there is any danger of having them overstressed. The middle two parameters would indicate how reliable operation of the PC would be and whether or not you would get power supply induced lock ups or glitches.
Power supply design is more art and component management than strong engineering application. Modern PC power supplies really are a result of iterative cost reduction and learned experience. A lot of "common sense" ideas are just plain wrong when applied to high current output switching AC/DC converters: I have learned that heavier is not always better and is often an indicator of an inefficient design. Fires are not uncommon in PC power supply testing and development and choosing the best power supply design is often a case of figuring out which company could best understand what the ashes were teling them.
myke
Mimetics Inc. Twitter
Er, not necessarily. Since heat rises, and the power supply is at the top, it shouldn't heat the case much anyway. Having recently switched from a loud PSU to a Zalmon power supply and lowered the voltage on my case fan from 12v to 7v (to make it less noisy), I've noticed only a minimal increase in temperature (still waybelow any max limits) and a blessed release from buzzing noises... I can now sleep with my PC at the end of the bed switched on, and more importantly, so can my girlfriend (admittedly not the usual review criteria for Slashdot ....)
P.
http://www.anandtech.com/showdoc.html?i=1841
Does the name Pavlov ring a bell?
A/C ripple would be 60Hz (or perhaps some harmonic.) A 10ms sample is _woefully_ too short to see it.
... it is my understanding that switching powersupplies shift the frequency to something substantially higher (1-10k Hz region.)
... approximate amplitude was the only conclusion you could draw, but to say "look, A/C" ripple noise is just plain silly ... especially as the A/C ripple would be so much larger than the 10ms sample duration.
Also, of more interest in a switching power supply than A/C ripple would have been the ripple from the power supplies own oscillator
Take a long (say 1 second) sample at a decent resolution (at least 120Hz for a A/C ripple, perhaps 100khz if you care for switching ripple) perform an fft, and look for the spikes at 60Hz and whatever the powersupply switches at.
What they were showing was meaningless noise
300 watts is more than enough for you.
Wattage isnt as important as the individual amperages that can be delivered on each line, though.
You want 2A or so on the +5VSB line, for example, if you want to use wake-on-lan or wake-on-keyboard.
You want a strong 12V if you have a ton of neon lights and bullshit like that. P4s and (i think) Athlons use the 12V line as well.
Drives used to use 12V to power their motors, and 5V for logic, but they all pretty much use +5 these days.
You can look at the drives to see what they need.
It takes all of maybe a half an hour to see what the amperage requirements for each component is, and then find an appropriate supply.
You see little cube PCs with Radeon 9700s and P4s running with 200 watt supplies, and its perfectly fine so long as the 200 watts is going to the right places. PSUs also run more efficiently at full load too, so it's cheaper on the electric bill in the long run.
I don't need no instructions to know how to rock!!!!
People said that about speakers too. Heavier construction meant less vibration-induced distortion.
So one company poured concrete in the base of their speakers. Even after the reason for their weight became clear, people actually still believed that they were the best speakers for that very fact alone.
"People who do stupid things with hazardous materials often die." -- Jim Davidson on alt.folklore.urban