I was gonna get 6950 crossfire but I was thinking instead of just getting a single gtx 580 and maybe later on getting a second. But I don't know if this motherboard is sli compatable. If it is, can someone recommend a good psu for sli 580's since I may add a second one down the road.
+1 to 6950 Crossifre (since I'm presuming an overclocked 2500k/2600k, and high res 1900x1080+)
(worth the extra 100$ over a single gtx 580, also the buy one now buy one later logic never works out because most likely by the time you need the second you'd be better off selling the first card second hand and buying the next gen single cards)
Corsair HX-850 for 6950 Crossfire and probably also for GTX 580 SLI (depending on overclocking, HDDs and other devices)
Note that the 6970 gets a 0.3 % win over the 570 as a single card but 570's in SLI take it from 6870's in Xfire by 5.8%
Here's some recommended 850 watters:
For comparison purposes , the list below contains performance ratings (10 scale) at jonnyguru.com / prices as per newegg on 01/13/2011 and ones w/ double asterisks (**) made it onto silentpcreview.com's Editor's Choice List meaning they excelled at both electronic and acoustic performance:
If ya go with twin 580's recommended PSU's include:
Antec CP-1000 - 9.5 ($150)
Corsair AX1200- 10.0 ($260)
Silverstone ST1500 - 10.0 ($380)
Antec High Current Pro 1200W - 9.5 ($310)
Antec TPQ1200 - 9.0 ($210)
Twin 570's will get ya 54 fps in the most demanding game (Metro 2033) in the Guru3d tests whereas twin 580's gets ya 65. Given that, I find most of the peeps I build for go for the twin 570's .....the 580's being a 42% cost increase for a 20% improvement. By comparison, the 6950 and 6970 hit 50 and 56 fps in X-fire on Metro.