FPS Problem

Can someone help i have a problem...i have a random fps drop in league that starts when half of the game is finished...the game begins normal with 130 fps but in the midle of the game the fps drops to 04 and it wont move...and it will continue every game i play...i set my graphichs at very low but nothing happens...thank you for reading and i hope u could gind an answer. (P.S. i updated my graphichs car the Nvidia quadro fx 880M 1gb)