Games slowing down after 5minutes of playing

[aritzzz]

I have a desktop pc with 8 GB RAM,2 TB HDD,2 GB XFX Nvidia GT630 Graphics,Intel Core I5 3rd gen processor,Windows 7 installed and auto-updated Avast Antivirus.Each and every game that I play slows down after around 4-5 minutes.I even played games like Call of Duty Advanced Warfare and Ghosts previously without problems but now it gets so slow that I can't even play low graphics games Assassin's Creed II properly.I am sure there aren't any virus problems and the cpu usage has never been more than 77%.Please help.

 

[BadActor]

Sounds like you might have thermal throttling issues with your CPU or GPU. Download HWMonitor and check your temps. Have you cleaned all the dust out of your PC lately?