I think you could expect 70-80 FPS normally. But obviously your PC is working fine, something's wrong with WoW. I've spoken to my friend which has CPU; 4,5 GHz, 2x GTX 680 (SLI) and he can reach 110 FPS in the new MoP zones. That's how demanding it is. Your GPU is a little better than mine, I'd say you should get around 5-7 better FPS in WoW than me, and I have around 70 in the new zones. It depends on the view angle of your camera etc.
Actually, maybe I'm talking about my FPS with everything on ultra expect shadows on High now. Because reduing shadows 1 step increases 10 FPS for me. Let me log in and take a look. I'll update this thread with a picture of FPS & place.