bignastyid :
I highly doubt you would see a difference in games going from a 4300 to an 8350 with a 750ti. Possible might even get worse with your current board if the VRMs cause the cpu to throttle to 1.4Ghz. So inorder to upgrade to the 8350 you'd need a better board. So you be looking at the price of the cpu and a decent motherboard for little to no gain in the area you are trying to improve(gaming). If any thing get a 1050ti or RX570 to replace the 750ti and save your money for an upgrade to a newer cpu platform(Intel or Ryzen).
For your current issue of FPS drops monitor your cpu frequency. Id be willing to bet that it's be caused by cpu throttling. Either from the cpu overheating or the overclock is too much for the board to handle.
Nah, my CPU doesn't go over 40 degrees, i've no issues with my CPU, I just need to run CPU intensive games, i don't need a new GPU yet, i'm gonna upgrade it around this december when i move out with my team to a new house, I'm going to be streaming games, so i'm starting to upgrade my computer for the future.