Will fx 6300 bottleneck R9 290

3Dns

Distinguished
Take a good CPU Cooler an OC your CPU in intensive games.

For example.

http://www.newegg.com/Product/Product.aspx?Item=N82E16835608018&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=
 

Deus Gladiorum

Distinguished
First and foremost, I have an FX-6300, I've overclocked it, and I have a GTX 770, so please, let me tell you from experience:
Yes it will bottleneck you (in CPU intensive games) and no, overclocking will not solve the problem. Yes, overclocking can help a lot, but you will still have frame rates drop anywhere from 30 to 45 (or maybe not at all) depending on the game you're playing. I've overclocked to 4.5 GHz and in games like Borderlands 2, Crysis 1, and Skyrim, I can drop to 30 fps or under, though with Borderlands 2 and Skyrim it usually drops me closer to 40. Plenty of games will end up having a bottleneck.

Some games that won't have a very noticeable bottleneck are the more recent, non-MMO multiplayer games like Battlefield 3 and Hardline (and likely 4) and Call of Duty and such. But there will be plenty of games like Assassin's Creed 4 or other games that will drop you well below 60 fps.

Your best option is to get an Intel Core i5-4440 if you don't plan on overclocking or an i5-4670k if you do want to overclock (which I recommend). An FX-8320/50 will not provide you with nearly as much of a performance difference. If you have yet to buy an AM3+ motherboard, then I highly advise you to try and save up your money for Intel.