I am planning to get a hd5850 or 5870, but i still got a free pcie slot available. So i think I am going to fill it up with a gfx card for folding. It have to be a single slot card. Any suggestions? Do you think a corsair 850w psu is powerful enough to drive a hd5870 a gts250 a single slot gfx card and a overclocked 920?