FPS drops with new pc

Hello,so i bought my new pc last week.It's components are:Intel core i5 4690,gtx 960 2gb,8gb ram,1tb hard drive.My problem is that whenever i play a game i start playing at 60 fps and then after 5 minutes it starts stuttering every 3 seconds,droping to 30 fps.When it's stuttering the game seems a bit blurry and the textures are loading.This happens on every settings i set in game.I would appreciate if someone helps me.Thank you!

FPS drops with new pc