That's real sexy right there, CPU and GPU OCs. I've only tried taking my Titan up as far as 1100.
I'm going to be installing my SB i7 3930k this afternoon... Dunno how high it'll OC, but I'd like to try to get it to 4.7 and compare with your results to see how much 6 core affects the game, if at all.
May very well be GPU limited with CPU speeds at 4.7 ghz.
Do you have hyperthreading enabled or disabled?