I'm running my Sapphire 4850 X2 2GB on a GameXstream 700W, and it seems to be running it with ease. It doesn't get hot, hasn't crashed once, so I'm sure you could run it on a good brand 600W. I think Sapphire have set the minimum at about 650W, but I say this is just a fail safe. I'm running all of my gear AND that card on a 700W, and it's fine. Chris.