HUGE fps drop- no clue why- HELP!

Hi, this is something very specific i need help with and I'm not sure where to post this...i hope I'll get the help i need here

I have a core2duo e6700 @3500(with a tuniq tower on it), ocz reaper each at 568mhz 5.5.5.15, BFG 8800GTS 640 OC2 all on a p5ne-sli(changed the passive cooling that came with the board to fan cooling).

now everything has been returned back to it's stock state after the cooling on the board was changed because the fan was broken, anyway, when i connected my computer back after changing fans i noticed a HUGE drop in fps.

i mean like maybe -70/60% performance.
(just to clearify things- fps went up maybe 10/15% after overclock..so....this isn't because the fsb/memory are stock speeds again)

I used to play crysis smoothly on 1280... now i hardly get up to 30 fps on 1024.
it ain't any of the graphic settings because nothing has been changed since.

i benchmarked the computer with 3dmark2005 and got 7335.

I have no clue whether it's in check my with system's capabilities or is something seriously f***ed up ?

please help! --- next step is to buy a new mother board.

thanks, yoni