It depends on what loads you currently receive. Put it this way, if you don't fully utilise the capabilities of your CPU currently (I.e. you always stay at lower loads), then adding more capability will effectively just make your CPU not utilise more capability.
Equally like upgrading from 16GB to 32GB RAM, if your PC never uses more than 12GB, the additional 20GB you're installing will just sit idle.
HOWEVER, if you're hitting peak loads on your CPU cores, overclocking will increase the performance of the CPU, therefore increase the performance of your game. But this is entirely application specific.
You will not see a performance boost in EVERY game. As some Games are GPU intensive, and not CPU. Whereas other games are CPU intensive, and not GPU. So for example, if you find that you are suffering bottlenecks when playing Fallout 4 in CPU usage, overclocking could generate large performance improvements as it is a more CPU intensive game.
In short - In depends on what games you're referring to, and if your CPU is currently holding you back.