game working poorly

Hello ive been playing this league, for almost 100 hours. Ive got a great pc and dont think the problem is there, since i have no problems whatsoever with other games, that are as heavy as this. While ive had no problems until recently, lately 50% of times i ope the mae, the graphics is at 100% for no reason, the fps is at 10, and i cnat play the game. id say this could be a late patch, that is doing this, ive got no explanation, have changed everything to lower and performance and nothing. Nothing else is being bottlenecked, my graphic memory is 16 and im using 8 max. only the graphics is going crazy...plz help or fix game, ty!!