I found out today that the framerate is CPU-limited. If I had a FX-6300 again instead of a Athlon II x4 635, there would be no bottleneck. I never thought that the CPU has anything to do with shadows and shaders.
I had a gtx 770 with an fx4300 and two monitors, didn't bottleneck.
Well I wouldn't do that now anyways, I upgraded my CPU and yeah, there was a huge difference.
If he's buying a gpu I would say go with a raedon 7770.