PSU 12v rails

fullfat · 11 Apr 2006 at 12:39

im just wondering if its better to have a PSU with twin 12v rails or to get one with 1 higher rated 12v rail.
i only run 1 cpu, 1 gfx card, and just one of each of these: dvdrw,harddrive and a fan.

what do you guys reckon?

Dutch Guy · 11 Apr 2006 at 12:58

Doesn't matter really for a single CPU/GPU system, the only time you could get into trouble with a dual rail PSU is when you have two X1900XTX cards in Crossfire or two 7900GTX cards in SLI as they draw a lot of power from a single 12V rail.

fullfat · 11 Apr 2006 at 14:33

ahh chers mate, i was a bit concerned about having 2 low 12v ratings with only 1 gfx card you see as my card is rated to need a high 12v output.

fornowagain · 11 Apr 2006 at 15:31

The only really significant difference between most single and dual rail PSU's is that dual rails have a 20A/240VA current limiter on each rail and maybe a voltage clipping zener diode. It's misleading, in 99% of cases there's only a single 12v source. It's the total combined wattage that matters. A crossfire system may be able to reach 20A. Most of the OCL's are set higher than 20A, but not all, so some trip out and the PSU shuts down.

Look for the total combined wattage for the 12v outputs. Don't just add the two rails together, you may not be getting as much as you think you are!

fullfat · 11 Apr 2006 at 15:44

the 2 rails are rated at

18a and 15a, but both together are rated at 32a

cheers