I have an OCZ TX 750. Another thing to add is an 1155 pentium G620 and 4gb of standard(1300MHz, 9-9-9-24) if it matters. Should i be able to OC? Also, if I were to sell the GTX 570 in my gaming rig and buy a 5970 for it, would a Cougar CMX 700 watt be able to run 2 5970s and an Intel i5 2500K?(just curious)
I run 3x5970 and it is ~870W AC at the wall that is ~800W DC but that is w/ a single core sempron, dedicated rig w/ minimal everything.
2x5970 would be tight on a 700W PSU and I think impossible with a power hungry i-5. You likely want a solid (Seasonic or equivelent) 800W PSU preferabbly one with a single giant 12V rail. Personally if you update the PSU I would go 1000W. It isn't much more and you gain the ability to expand to 3x5970 someday.