So I recently noticed that my AMD Phenom 9950 X4 @2.6 was bottlenecking my GTX660, so I am upgrading my cpu/mobo.
The amount I am spending will be around 170$ for the CPU+mobo(+RAM).
I was thinking of a Phenom II X4 965 BE as CPU but I'm not sure if that's the best I can get.. I saw in the Far Cry 3 CPU benchmarks that the FX4xxx had much more FPS than the Phenom X4 965. But that was paired with the HD7970.