Someone explain: 61.76 drivers get me worse 3dmarks, and oc worse?

Alrighty. Let me get to he point. I put in the whql certified 61.76's and my fps in wings of fury dropped over 140 (fps). I ran it at the same 505/960 as usual, but it crashed at proxicon. HUH? Then, i put it down to 500/960, and it still crashed. I put back in my old 56.72's and I have my original scores back. Any ideas?