Run your games and see how you do.
That is the ultimate test.
If you want to do some experimenting, here are some ideas:
a) Run YOUR games, but lower your resolution and eye candy.
If your FPS increases, it indicates that your cpu is strong enough to drive a better graphics configuration.
If your FPS stays the same, you are likely more cpu limited.
b) Limit your cpu, either by reducing the OC, or, in windows power management, limit the maximum cpu% to something like 70%.
Go to control panel/power options/change plan settings/change advanced power settings/processor power management/maximum processor state/
This will simulate what a lack of cpu power will do.
Conversely what a 30% improvement in core speed might do.
c) Experiment with removing one or more cores/threads. You can do this in the windows msconfig boot advanced options option(now in task manager).
You will need to reboot for the change to take effect. Set the number of threads to less than you have.
This will tell you how sensitive your games are to the benefits of many threads.
If you see little difference, your game does not need all the threads you have.
Some time back when CRT monitors were the only thing, it was the graphics card that refreshed the crt.
It was found that 85hz was necessary to keep a steady non shimmering image.
I suspect that today, any fps faster has to be encountering diminishing returns.