Computer lags after being on for an hour.

[IveFallenAndICantGetUp]

I'm not sure how to explain this, but basically if my computer is on for an hour or more, all my games lag and the FPS is dropped drastically. I have NO clue why this happens. It just recently happened. Maybe its a driver error?

 

[MusenMouse]

Have you checked RAM and CPU usage? If either or both is high when you have the FPS drops then you might be bottlenecking with too many programs running. You can try to alleviate this by typing msconfig in the windows search bar and turning off programs that you don't need on startup, and then restart to see if the slowdown is still happening. If issues persist then I suggest doing a virus scan on your computer to make sure malware isn't running a muck on your computer. My recommendation, if you don't have a favorite, is the free version of Malware Bytes.