ATX spec voltage fluctuation

[dredd2929]

I have a PC Power and Cooling 510 SLI in my system. I read the results of Tom's Hardware's PSU recent stress test of this unit, and he reported that it stayed within tolerance on all rails. That's all well and good, but the author states that the ATX spec allows for 120mV fluctuatin on the 12V rail. Using my ASUS PC Proe utility, I'm seeing the +12V rail fluctuate from 11.84V to 11.776V; the latter voltage is a drop of 224mV. Is this something I should be worried about? I'm thinking this may be because the motherboard probe is reading the voltage at a different point, perhaps some minute resistance between the PSU and the "virtual voltmenter" is giving rise to the increased voltage drop?

J. J.

 

[John]

Please read through this thread.

http://forums.anandtech.com/messageview.aspx?catid=27&threadid=1649622

 

[OdiN]

Yeah test with a multimeter for accurate results. I wouldn't trust the onboard stuff as much. Even at 11.7V that should be okay....some supplies vary. If you have a lot of stuff using 12V it can lower the total output. I think you're fine though.

 

[dredd2929]

Thanks guys.

J. J.

 

[Mark R]

ATX spec: must be within 10% (+/- 1.2 V), recommended to be within 5% (+/- 600 mV).

 

[John]

Originally posted by: Mark R
ATX spec: must be within 10% (+/- 1.2 V), recommended to be within 5% (+/- 600 mV).

Please keep in mind that the 10% value is for the -12v, and for the +12v(1) on a dual rail psu (peak load only). All other rails should be within 5%, and IMHO optimal is <2%.

http://www.formfactors.org/developer/specs/ATX12V_PSDG_2_2_public_br2.pdf

 

[dredd2929]

Well it seems that my PSU is well within ATX spec then, I don't know what the reviewer on Tom's Hardware was talking about.

J. J.

 

[Budman]

Originally posted by: dredd2929
I don't know what the reviewer on Tom's Hardware was talking about.

J. J.

they dont even know what they're talking about themselves.