Hey, I am planning out a build and want to get a HIS 7950. How much of a bottleneck would there be if I used a AMD Phenom II X4 965 Black? Should I spend a lot more money for an i5?
I have a GTX 770 and an FX-6300 so the levels of bottlenecking are roughly equatable. It exists, and it's rendered 1 game (Crysis 1) unplayable for me on Ultra or High settings (and medium sucks). It also makes Borderlands 2 an occasional hassle (and sometimes sort of feels unplayable due to lack of motiob blur) because I will sometimes experience drops to 43, 38 or 30fps but for the most part I'm at or near 60. Skyrim also has the very infrequent drop down to 45 fps, but it's rare enough that I really don't care too much. For other games, it's negligible or non-existant such as in Battlefield 3, Crysis 2, or the Witcher 2. Personally, I wish I spent the extra $100 on the i5-3570k and just changed my board to a similarly priced one to accommodate. The other advantage to going for an i5-3570k is that it's far more future proof than the Phenom in case you want to upgrade your GPU again in the future. An i5-3570k currently doesn't bottleneck a GTX 780 even from what I hear, so that's something to take note of.
Bottleneck will be reduced if you get a good cooler too and overclock the CPU. If you are not comfortable with overclocking , then go for a different build
I've overclocked my FX-6300 from 3.5 GHz stock to a stable 4.2 GHz (passed a 24 hour Prime95 test) and then again to an unstable 4.6 GHz (failed after 12 hours). For either overclock, the increase in gaming performance was insignificant and resulted in a 6 fps difference at most.