Specs

Windows 8.1 Pro x64
Intel Core i7 950 @ 3.68 GHZ
6GB DDR3 RAM (Triple Channel)
EVGA x58 Classified SLI MB
EVGA Geforce GTX 680 (28" Monitor 1920x1080 via DVI)
Geforce 335.23 Driver (Latest)

Tried everything from max settings to lowest settings.

Average FPS 25-35
In cities around 14 FPS average
In wilderness FPS jumps at random from 10 fps to 80 fps and all over.

Game is absolutely unpleasant to play, I went to extremes of formatting PC installing windows 7 x64 clean install, then reverting back to 8.1 when it provided absolutely no benefit.

I am desperate for any type of assistance. I really want to enjoy this game, but after 5 minutes in game I get so frustrated over how awful it runs that I cannot bear to continue playing.

Thanks in advance.