7900gs sli power requirements

[Lahire149]

I have a 520w (+12V 33A) OCZ Powerstream non-sli version. The SLI version have +12V1 (20A) and +12V2 (18A). And I was wondering if I just used a dongle adapter if my psu would be able to cope with SLI 7900gs. I've read that a single 7900gs uses 22A but in SLI the requirements is only 28A.

Does this sound correct to you? Will my PSU work?

 

[3ssence]

520W should be enough power for 2 7900GS cards.

 

[Lahire149]

wattage isn't in question. Amperage is in question.

 

[BarnyMiler]

I'm not going to pretend to be an expert, but I think that as you pointed out, the fact that the SLI-Certified PSU has multiple +12V rails means that each one is capable of powering an individual card on it's own. With your existing PSU, you'll be running 2 power-hungry cards off the same rail and may experience issues.

You may be able to run SLI with the existing PSU, but might experience problems during peak gaming usage. So...long story is, you will be better off with an SLI-certified PSU.

Most of this is based on my own experience with an Antec 480 Watt PSU, which was not listed as SLI-certified even though it did have 2x +12V 18A rails and had 2x PCIe connectors.

I was able to hook up 2x 6800 Ultra cards and get them to run in SLI on that PSU, but after a while (after adding a 2nd hard drive, etc), I began to run short on power (or so it seemed). After gaming for a while or while playing games like Oblivion which were very GPU intensive, I'd get strange crashes and warnings from the nVidia Control Panel saying the card was not receiving sufficient power.

I bit the bullet and upgraded to a BFGTech 650 Watt SLI-Certified PSU and haven't had any problems since. Well, except for the noise that the new PSU fan emits which is pretty loud!

So, maybe try it and see first! You'll know pretty soon after trying it if it works or not.