As far as gaming, that setup would be great. A bit overkill unless your need that i7 for video editing/rendering/ or anything intensive like that. Otherwise you could go with a 4670k i5 and see maybe a fps lower or two vs yours and save about a hundred dollars. Also, two 770's kick butt, but some games don't sli well. I don't know what they are as bf4, cod ghosts, borderlands 2, and all games that I play sli very well. But just keep in mine that sli doesn't always work. But when it doesn't your working off just one card, and even at one card the 770 does a very good job at high end graphics by its own lonesome self.
Also, don't get the 690 or titan unless you are going to be running multiple monitors, and the titan black just came out so if you were to spend that much on a gpu, get the black. Otherwise id recommend just a 770 for very good high end, 780 will offer ultra on just about everything under the sun single monitor wise. The 780ti will crank out ultra on single or multiple monitors. Titan/titan black and really for 3-4 monitor setups and bragging rights, not so much needed to be able to play.
Pc 1600 is really all you need for gaming, a bump up wouldn't hurt, but normally not really budget/performance nice.
Also, 6gb is needed for most games, 8gb is the norm since that means 2x 4gb sticks which are more commen and better off than a 4gb and a 2gb. 16gb is really only needed for intensive programs or activities like video rendering/cad/3d work and such.
Hope that helps
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