Just try to make your graphics card and the fan clean. And make sure the plug is removed and the power supply is turned off. And before you bring the graphics card in the hand / touches barrel with one hand on your body because you can destroy your graphics card because of Electrostatic voltage otherwise.
Sorry've omitted something!
Anyway I play so with 80-200 FPS LoL but after a short time about 5 minutes sprint the game easy to 0-20 FPS. A few days ago everything went perfectly! I've updated all the drivers and graphics completely runtergestellt, what should I do ????
Just drop your system, ie CPU, video card etc!
Maybe overheating of your PC? If only as an idea ... because it is very hot since few days.
Otherwise no plan, I'm sorry.