slow games with no fps drops!

[no.1_bc]

so i had this good computer since 11 months ago and the last week when i was playing league of legends i start to notice the game was going a little bit slow, which was weird because the fps remain in 50 and up, and then suddently IT REALLY starts to go slow for about 7 seconds but again, without any fps drop, and i dont understand what is making it

i also update my nividia drivers so....
this also happen in other games

 

[rgd1101]

full system spec? what game? what resolution? what detail level?
what the cpu/gpu temps and usage during the game?