A friend of mine is running 2 x GTX 770 Superclocked in SLI.
The game is running in maxed settings 1920 x 1080p with 70 fps. But with a AMD CPU though. I guess he woud have more with an Intel.
Depends, the '8' core Piledriver CPUs are pretty good in Crysis 3 cause it's pretty multicore optimized