There is NO useful cpu upgrade available for that motherboard.
If your games are cpu limited then look to a more modern kaby lake or ryzen cpu/mobo/ram upgrade.
If you play fast action shooters, then a graphics upgrade might be OK.
At least, a new gpu can be carried forward to a new cpu upgrade.
If you buy a new graphics card, make the jump big enough so you can see good results. GTX1070 class card.
Try your games with reduced resolution and settings. If your fps increases nicely, your cpu is strong enough for a graphics upgrade first. If no change, you are cpu limited.
As a second test, see how many threads you are actually using.
You can do this in the windows msconfig boot advanced options option.
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.
Another upgrade that you might consider would be a SSD for your C drive.
It also could be carried forward.
240gb or larger Samsung EVO