I'm in pretty much the same situation. I currently have an i7-3770, 8GB memory, and EVGA GTX 770, 750W PSU. I've had this setup for some time now and I too am somewhat of a frame rate whore. I want to upgrade but don't want to fork over >$700 for the 780 Ti. I think spending ~$300 for a second GTX 770 is the right move especially after watching benchmarks where they compare dual 770's against single 780's, and other cards. If this were a new build I would absolutely go with a single 780Ti but i already invested in a 770 a while ago.
I'll honestly wait and see if the price of the 770 comes down even more as I don't really feel the need to upgrade before Star Citizen comes out. Watch Dogs may change that though....
My first post on the forums!!!!
