maddogfargo :
No, it won't bottleneck.
Intel i5 and i7 and also FX 6300 and 8300 series CPUs won't bottleneck a single high end GPU in modern, multi-threaded games.
They also won't bottleneck most 2nd tier Crossfire/SLI setups either, such as R9 280 / HD 7950.
FX 6300 with dual R9 390 or GTX 980ti will start to have a bottleneck in some games.
Example: I had an old Phenom II x6 1090T @ 4.0GHz that would fully load both of my HD 7950 GHz ed. (R9 280) in crossfire with Crysis 3 on max details except for 2x SMAA (* Tom's recommended AA mode for best performance/appearance balance). CPU would be around 90-95% usage on all 6 cores. GPUs would both be at 95-99% usage. No bottleneck, well balanced, average FPS in the 50s.
Midrange OC of 4.4-4.6GHz on FX 6300 or 8350 will be plenty to handle pretty much any single GPU.
Sorry to revive this thread, but you're saying that an FX-6300 won't bottleneck an R9 390. I currently own an FX-6300 (clocked at 4.9 GHz) and an R9 390, and I'm getting bottlenecked out the ass. In BF4, my CPU utilization goes up to 95% and I'll get 48fps (not always, but it's ridiculous that it would go below 60fps at 1080p).
I need to upgrade my CPU, so should I go with an FX-8350/8320? I don't want to be stuck in this same situation.