What to look for in a PSU

[tgxiii]

What specs should I look for in a PSU? I know that wattage doesn't mean much if the rails are weak. What numbers should I look for in the 3.3, 5, and 12 (the minimum)?

Please no responses like "just get an Antec" or anything suggesting to get a certain PSU. I just want to know if the power supplies that come with cases are good enough or not.

[bailey]

the best thing I can suggest it to always use a supply with a good brand name like enermax, antech ect.
the wattage to look for will depend on how much and what hardware you plan to put in it,
there is no cut and dry what is best for you, its like everything else in the system the is researched to what you want it to do for you.
as far as the psu that comes in a case, I have seen a lot of the cheaper deer and many off shoots of deer supplies in new cases
stands to reason that a 30 dollar case is not going to have a 70 dollar psu in it, new systems of today usally have at least a 350 enermax silent 2 fan supply, for a starter suggestion.

the first thing I do with a new case is to replace the psu with a new one of my choice, and trash the one I removed, or buy a case without a psu, and install a known good one.

[Dax_Brandy]

the actual values in the rails should fall within the +/- 5% tolerances. and just make sure you don't overload the PSU.

[tgxiii]

The thing is, not all good PSUs are big-name brand. I got this Achieve power supply for only $22 shipped and it's been running great.

+3.3v = 30A
+5v = 50A
+12v = 25A

Those are the specs according to the sticker on the side of the PSU. What I would like to know is what is a good number of amps to look for in each rail if I were to run a typical gaming computer. Who knows, I might run into another good find.

[Xtreeme]

About same specs ya got now is what to look for. But amps dont tell the whole stroy either LOL. After all-VxI-watts. Volts times amps =watts so Just cause it says it supplies so and so amps doesnt mean it does. Look at how many 400watt psu generics cant deliver a solid 250watts even!!! Look up some PSU reviews you'll see what we mean. There are 400watt car stereo amps that a good 100watt amp kills! Watts arent just watts. Thats the biggest understamation when cosidering these things. Now the Achieve is said to be good-from another forum member. So I bleieve it is. But dont fool yourself thinking all cheap psu's are = in any way shape or form! That maybe just a lucky find-one in a million so to speak! Also look at the POT (Potential "ON" Time life) hours aswell. Some just plain'ole last longer. My 420 watt TTGI lasted almost 3 years. Great specs on amps! Then came the 9800np and it died in 2 weeks flat.

[tgxiii]

I guess there's no way to know how good a PSU is without trying it out, huh?

[Dax_Brandy]

Originally posted by tgxiii
I guess there's no way to know how good a PSU is without trying it out, huh?

I agree.. sometimes a good brand of PSU breaksdown, on the other hand a no-name brand lasts so long.. it all depends.. but the last thing that you will consider also is the aftersales support these manufacturers give to customers..

[Bovon]

There is no absolute way to determine the very good from the very bad without a decent background in electronics and knowledge about which brand of components are good, bad or somewhere in between.

The major failure in a computer power supply is the two large filter capacitors inside. When these dry out, they begin to "leak" voltage to ground..little by little..this leakage increases until the capacitor shorts out and kills the power supply. When the filters short out, they generally take the rectifier diodes and switching transistors with it...switching transistors alone can cost $25 or more bucks a piece..and there are two of them.

Why do capacitors go bad?... several reasons, one is poor manufacture and two is heat buildup in the PSU case. These filter capacitors have a gel inside, and when this gel dries up..it will then begin the failure downhill run.

One other by product of a failing PSU filter capacitors is increased "noise" or hum... This noise/hum is a carry over from the filter capacitors failing ability to filter properly..this noise or hum (not audible) will play he** with analog signals from a modem...screw up video and create all kinds of Windows anomaly's. All very difficult for any layman...even a good electronic technician without a workbench full of test equipment..like an oscilloscope for instance.

These so called motherboard and PSU testers with some LEDs on them are just to make a few bucks...(for the seller).

[joker_927]

One of the coolest articles ever

[Xtreeme]

I know what you mean about useing a oscilliscope. The current ripple in alot of psu's is terrible. Ive seen it first hand. And the signal noise inside a pc is terrible too. Even when working properly! I mean think about. All those signals travling over wires embedded in substaraite layers is good but not 100% isolated. And then surrounded by a metal shield (case) keeping it all trapped in there and also acting like a anntenna aswell for outside interfearence. Plastic cases keep sounding better all the time! Now if per say-DUpont or somthing would make a rugid platic/rubber case-Im all there. Quiet, strong and will help isolate "some" signal noise. Would kill case vibration in a instant!
*I'm running for a patent now!* LOL.