Ah I'm the same
I just did Crysis 3 maxed. I have an EVGA GTX670 FTW (which I love - delivers same framerates as a stock GTX680) and it managed at 1080p, 2x SMAA and ultra. Though I think if the performance had been even slightly lower I'd have started dropping settings. I haven't tried a framerate counter on it, but I'd estimate framerates mostly in the 30s, and 40-60fps in less demanding areas. Based on my experience, I'd advise a GTX770 for these settings. A GTX780 might be a bit excessive - hard to justify that price for a fairly minor performance gain.