I want to know which one will bottleneck a 7950 more. I know both of them will, but I'm looking toward the Pentium because of the upgrade ability
I understand the point that you have made about the upgradeability.
Do you already have the 7950? Might be advisable to pick up a 7870 (or similar performing card) and pair that with the 760k. That'd play most games on ultra at 1080p.
I already have a 7950 but I wanted to know because my mobo and CPU died out
I have seen people on youtube using a 750k and 7950, allowing them to play BF4 on ultra settings. So the 750k is definitely the best bang for buck, but the trouble is you won't be able to upgrade. I can't make that decision for you.
If I'm not mistaken, he can get a FM2+ motherboard for the 750k, but then he's taking a game on Kaveri's CPU performance.