420w/520w/600w Power Supply (Diminishing Returns?)

[foodfightr]

First off, let me say that I was considering purchasing a 520w PowerStream power supply from OCZ. I was reading a review and I noticed these two quotes I am concerned about.


Hmm... This makes me think there might be some better value in the OCZ 420ADJ! If you look at the specs of a 420ADJ, you'll see that you only lose 3A on the 12V rail. Trust me, you can live with that. The extra wattage for the 520W is made up for on the 5V rail! 30A versus 40A! .... Wasted power.

This makes me wonder if the 520w is worth it or not? What if I decide to go all out and purchase the 600W, would I be looking at pretty much the same problem? Or is this all a misconception?


I then cranked the 12V up to the maximum specified amperage as per the label. This put the 12V at 33A while the 5V was at 20A. No problems. In an effort to perform my max load test, I then began cranking up the 5V and, just like clockwork, the rails started bouncing about so frantically, there would be no way you could run a real PC off of the power supply. I then proceeded to push the 5V up to 40A and the 12V dropped all of the way down to 10.24V! I could stabilize the power supply by turning the 12V up even higher, but temps were already at 47.3C which is hotter than any other power supply I've tested so far! So THAT wasn't a good solution. You can't even get the 5V up to 30A and stable when there's only a 10A load on the 12V!

I plan to upgrade to SLI in the future, so I expect to have a heavy 12V load.

Review Link (http://www.slcentral.com/ocz-powerstream-520adj-power-supply/index.php)

Please post your comments and opinions on the two excerpts I posted!

THANKS!

[cmay119]

Watts= Amps*Volts correct? Going on that information, there should only be 50watts made from the +5v rail on the 520ADJ over the 420ADJ. 10A*5v=50Watts more from the 520ADJ over the 420ADJ

3A*12v=36Watts more from the 520ADJ over the 420ADJ

we're still missing 14watts from somewhere. Is there more amps on the +3.3v rail on the 520ADJ? 4*3.3v= 13.2Watts. Perhaps OCZ rounded up 1watt for the 3.3v rail on the 520ADJ.

I just wen't and checked newegg.com and it seems that OCZ changed the 520ADJ to an "SLI" version with 2x+12v rails measured at 20A and 18A just like the 600ADJ, but the 600ADJ has 46A on the +5v over the 40A on the +5v of the 520ADJ.

Interesting stuff, I'm not sure whether going with the 520watt over the 420watt is a better choice or not. Definately an eye-opener though, if that's true.

[jahjahbinks]

For your second excerpt, did that person tested with 600W PSU?

[Micutzu]

...

The total power of the PSU is lower than the total power on each rail, due to a number of reasons, wich can be either electrical or heat related. The 420W might even support the same max ratings on each rail that the 520W does, but it might not support the same total power, thus the lower rating.

[Welz]

you dont have to worry about getting a crappy psu with OCZ, and im sure even the 420watt could take a single 7x series or x1k series gfx...

if SLI is in your future, i would get the 520 watt

[Dave in Daytona]

Same answer as EOC.