I had the 512MB version of that card and now I have a XFX 5770 XXX version.(sold my other PC with the powercolor) The card's don't really run hot and overclocking them will only improve results til about 875,1300. Beyond that performance seems to actually drop, perhaps due to error checking or because the video card isn't powerful enough to use higher clocks anyways. In performance test (3D simple), on the stock 875,1300 OC I got 1921, and overclocked to 900,1300, I I got 1890.7, 30 less points with the higher overclock. It's basically that across the board. and when I did 900/1400, the performance dropped even more. I hope this helps.