@ zqa90: Fair enough, mate, not everyone knows how to do that kind of maintenance and it was a bit of a long shot that those would help significantly anyway.
As a last resort, update the system software: Chipset drivers, sound and video drivers along with any mouse/KB/monitor drivers that may be available through the respective makers websites, although I feel the root cause is just the old CPU is struggling with current, better threaded titles, as you already suspect.
Intels 9XXX series should paper launch October but general availability won't be until later, expect launch prices to be high.
If you mainly, or exclusively game monitor rez should make the decision of upgrade choice: Intel has a significant advantage at HD resolutions and a VERY small advantage at 2K, once you move to 4K rez there's no practical difference between a i7 8700K and a R7 2700X.
If you regularly use other software check how threaded it is, it may be to your advantage to have better threaded performance ( AMD ) by trading a little gaming performance ( Intel ) for it.
Whichever way you move, you'll need to do a full reinstall of Windows AND your software to avoid future problems but link your current Windows license to a Microsoft account first:
https://www.windowscentral.com/how-link-your-windows-10-product-key-microsoft-account AFAIK this will transfer even OEM or builder licences to the new system.