Your PSU will only use what is needed. If a PSU is 1000w, that means it is capable of powering a system that requires 1000 watts. Just because it has a high wattage doesn't means it uses it all. My reccomendation is the EVGA SuperNOVA G2 750. It is very good quality, comes with a 10 year warranty, and leaves room for that possible two way SLI. I've heard of people having problems with the CS series from Corsair, but I haven't owned one so I can't say much about it.