Hmm, the 770 Lightning actually has a factory overclock. Did you recently get the GTX 770, and is this problem only occurring in Crysis 3? You could try underclocking your 770 to reference clocks and see if that alleviates the problem, if it does, it means your card is unstable with its factory overclock, in which case I would RMA it. If not, you might want to try a newer driver revision, as I've heard of all sorts of problems with the 320 Nvidia drivers.