Psu for dual gpu's

[asantesoul]

I've just recently purchased my new sandy bridge board along with a 2500k processor. I'll be getting the rest of my parts later this week and the rest of next week. My question is what kind of psu will I need for two gtx 570's? And what about 2 6960's for crossfire? Will I benefit more from using a single gtx 580? Please help me out everybody !!

 

[JackNaylorPE]

For twin 570's, a 850 watter is more than enough.

For comparison purposes , the list below contains performance ratings (10 scale) at jonnyguru.com / prices as per newegg on 12/31/2010 and ones w/ double asterisks (**) made it onto silentpcreview.com's Editor's Choice List meaning they excelled at both electronic and acoustic performance:

Antec SG-850 - 10.0 ($250) **
Antec CP-850 - 10.0 ($120) **
XFX 850W Black Edition 10.0 ($130)
Corsair HX850 850W - 10.0 ($170)

Antec TruePower Quattro (TPQ-850) - 9.5 ($150)
Corsair TX850 - 9.5 ($130)
Seasonic M12D 850W - 9.5 (NLA) **
NorthQ Giant Connector 850W - 9.5 (NFS)
Etasis ET850 - 9.5 (NLA)
Silverstone Zeus ST85ZF - 9.5 (NLA)

Enermax Revolution 85+ 850W - 9.0 (OOS)

Thrmaltake Toughpower XT 850W - 8.5 (NLA)
OCZ Z Series 850W - 8.5 ($165)

NorthQ Black Magic Flex 850W - 8.0 (NFS)
Coolmax CTG-850 - 8.0 (NFS)

SilverStone Decathlon DA850 - 7.5 (NLA)
Enermax Galaxy DXX 850W EGX850EWL - 7.5 (NFS)

SilverStone Strider ST85F - 7.0

Silverstone Element ST85EF 850W - 6.0


OOS - Out of Stock / NFS - Not For Sale / NLA = No Longer Available

Based upon cobbling together data from numerous reviews, the 6970 and 570 are two of the most closely matched cards I have seen from the 2 camps. Here's some data based upon tests at hardware heaven, guru3d and benchmarkreviews:

Total FPS (sum of tests on 3 sites) single card / SLI Xfire

570 - 524 / 873
580 - 616 / 953
6950 - 479 / 751
6970 - 526 / 825

$ per frame single card

570 - $0.67
580 - $0.83
6950 - $0.63
6970 - $0.72

Scaling %

570 - 166.60%
580 - 154.71%
69xx - 156.78%

 

[asantesoul]

Thank you very much for the quick response! I'm leaning
Towards getting the 6950 only because of the recent discovery of it's ability to be unlocked to a 6970..I wanted to get either corsair psu because I can't get good deals..aren't the hx and ax models good?