What sort of wattage we talkin here?

To Sli GTX 670 Stock or if I Overclock the cpu and gpu's?

Thanks

Corsair RM750 SLI compatible?

650-850W... A former poster here had a 3570K running at either 4.2 or 4.4 and SLI GTX670 and ran it at a 650W PSU... Corsair AX I think.

Go the sweet spot, Corsair 750W.