I am running gtx 680 in 2 way sli with a 3770k at 4.2ghz and I am being out performed by a single 680 on crysis 3, I have all the latest drivers, the CPU clock is stable, and all temperatures are fine, what could the problem?

I have seen benchmarks of a single 680 playing crysis 3 at maximum settings with about a 55 fps and my 2 680s struggle to achieve that.