The 8320E should be fine on that board, to about 4.2-4.3GHz which is honestly the best viltage/heat ratio for that cpu. It'll go higher, but not really worth it as you'll really need to invest in a very good cooler. Being only a 95w cpu, you have a little more leeway vrs the 8320. Something along the lines of a Cryorig H7 would be good.
As far as bottleneck, that's a moot point. In any heavy gpu related game, it'll do fine on the 8320E, it's only on some of the more intense cpu games that amd cpus have issues compared to Intel. AMD just isn't as strong on single thread performance, so even a lowly i3 can outperform an FX in games like skyrim. In other games like BF4, the 8350 came in second only to the i7's, not being able to match IPC in thread to thread counts, so there's that.
Basically, there will be games where you have settings high enough to use a lot of cpu, and still not use all the gpu resources, but in others you'll have a better balance.
OC that FX, it'll help. Just don't expect miracles.