FPS DROP DOWN from 120 to 60 fps O_o

[PingOVER9000]

Lately (these 2 months) my fps often drop down from (a costant) 122 fps to 80, also 60 fps.. I dont why the reason..

 

Everything seem fine and in other games didn't happen like seeing spark  lagging issues..

For now I switch the option for playing at 60 fps.. and seem ok for now, but I dont know how to explain this fact..

 

Some gentle souls, can give me some advice to resolve this problem? 

 

Thanks in advance

Edited November 5, 2019 by PingOVER9000

[Mitne]

There might be multiple reasons. Specification would be helpful.