I only have a 770 and thought i was unable to run the game. Even with anything on low, i would get stutter, drops, low fps, etc.
Today i set the Frame limit back down from max to 30, and then 45, and then 60, with the occasional screen tear the game is finally playable, it's butter on some maps. Even with a few settings put back up to medium, i haven't really pushed the limits but the game is finally playable for me.
I'm aware i'm outing myself as the idiot, but just incase your performance is unplayable, try lowering the frame limit.