I have a Powercolor 7970 and i was also dissapointed when i plugged it in and saw that it would get 540-610khs. Guys you are only going to squeeze 700 out of a 7970 after you have about 20 hours of experience tinkering with these things. I have tried many configurations and am getting a feel for how to tune it. I can run 600 comfortably, and 690 fi i push it pretty hard. If i push into the 700s my driver crashes after about 10 minutes. I think it crashes because my memory speed is cranked up but the temps seem fine with no rejects or HW errors. I heard it could be a Windows 7 bug.