I currently have a 750w psu for an i7 920 at 4ghz, 6gb ram, 3 7200 hds and a gtx 285 sc. I am going to sli another gtx 285 sc and add 6gb more ram. Will 750 still be enough or should I get a 1000w? Thanks.
Unless you do some major cad work or hd video editing, youre not gonna use anywhere close to 12gb let alone 6. Save your money if you dont do one of those things. You should be fine with the 750w corsair. A 1000w is really only needed when youre running tri-sli. If you wanted to have a little extra juice, i would get an 850w pc power & cooling. You should be fine with the one you have now though.
As a rule of thumb you want to check the amperage for sure. BUT, like you guys said, it's freakin Corsair. With a Corsair 520hx, 550W,620hx, etc, you're golden on just about any sinly video card out right now, within reason of course. Same goes for PC Power, they're awesome. That 610W they make has amperage up the ying yang.