My 1090t didn't bottleneck my 6950 and that's only .2ghz faster. I was getting around 45-50 in crysis 2 with the high res and dx11 with very rare slumps to 25-35 which is still higher than his average. Would 200 MHz affect this? This was with the single 6950 btw.
In short I don't think 200mhz would screw the frames that hard but I could be wrong, I think it's more likely the driver uninstallation problem. Try a fresh install of the os if possible.
Edited by UpgradeSolution - 1/6/12 at 3:14pm