Are dual 12 volt rails really that important for sli?

[cich1012]

Is it really that important for have dual 12 volt rails?

I have a 620 watt psu with one rail for sli, am I cutting it short?

 

[prosser13]

It depends how many Amps are on that rail. You got a figure?

 

[cich1012]

well the funny thing is that I bought a skyhawk gm620sc power supply that stated it had 2 12 volt rails. then they were caught lying on the box when indeed they only had one 12 volt rail On the box it says each rail has 20 v but how can that be when there is only one rail...

so i assume its 40 amps.

on the 3.3v output it says 45a?

 

[prosser13]

The 3.3V rail doesn't matter. The best idea is to look on their website and search the net to try and find the real figure. How'd you know it doesn't have 2 12V rails? And you should ask for your money back by the way.

 

[cich1012]

theres a ton of reviews on the psu and when the opened it up, it has only one 12 volt rail.
when they were contacted, they admitted it and are looking into revising it..


should dual 7800 gtx have a dual rail psu?

 

[rise]

those sky hawks are questionable at best, aside from the rating snafu before.

for example, i saw one of their new units with dual 12vs 20amp each but a combined max output of only like 27a as i recall. search "skyhawk" in general hardware and theres a recent thread about it.

for sli you really should be looking at a big single rail imo.

 

[Topweasel]

Originally posted by: cich1012
theres a ton of reviews on the psu and when the opened it up, it has only one 12 volt rail.
when they were contacted, they admitted it and are looking into revising it..


should dual 7800 gtx have a dual rail psu?

No What matters is the combined amps on the dual 12v vs. the total on one. The Dual 12v PSUs the usually beat the best single rail PSUs in that regard. On the other hand the two rails might be seperated to different parts in your machine, so one rail could be being used to much and he othre migh have more then neough to spare. This is why one with an adjustable rail setting would be king.