This is incredibly low for even a SINGLE reference 780, for two ACX SC 780 in SLI you should be geting from 90 to 100 fps with those settings.
I think that what is probably your problem at Nvidia control panel, one of the cards being setted for PhysX.
Could you check it?
I don't know if a 2500k bottlenecks two 780, but if that were the case, it surely wouldn't be that low, and though not reaching what it could reach, your fps would be higher than what they are.
EDIT: Sorry, with SSAA on, it should sit around 70, not 100fps as I told.
So from 70 to high 50s this could be a CPU bottleneck, though I still doubt it.
Edited by tiaolipa - 8/16/13 at 12:43am