No, the 3930k will not provide any performance advantage over the 960 in games. Yes, you would get a measurable, (but barely noticeable) frame rate advantage in CPU limited situations. However, these are relatively rare unless you're running a powerful graphics card at low resolutions. (Nobody would do anyway, and even if they did, the framerates would already be so crazy high that any CPU limitation would be of no consequence). At a resolution of 2560x1600, the practical bottleneck will always be your graphics card, even with a GTX 690. The i7 960 is already plenty fast enough to feed your GTX 690 as fast as it can go at this resolution.
But more seriously, why get get a system that is utterly overkill just for bragging rights? Surely the bragging rights go to the person who puts together a system that's fit for purpose? Really, hexacore is of no advantage whatsoever over a quad in games. Not a single one of your frames per second will be attributable to the extra two cores. Actually, a quad i5 or i7 on Z77 will be better since you can clock it higher. If it's fully redundant computing power you're after, why not go the whole hog and get a dual socket, 16 core Xeon setup?
Having said that, there are situations where X79/Hex does make sense, eg if you're into simulations, modelling or video rendering - something that will actually use the extra cores. But not for games.