Would, say, a Phenom II X4 965 BE bottleneck a GTX 660? I currently have a GTX 460 768MB (built this rig right when the 460's came out, and the 1GB versions were much harder to find), and I've been thinking about upgrading in the near future when I get some cash. My 460 serves me well for right now since my monitor only goes up to 1440x900, but I plan on getting a 1080P monitor soon, as well.
OC'd to 4GHz, I don't think so imo.