My Game freezes and stop responding. makes a window notification sound

i tried everything!! reinstalling the game, windowed the game and done several acts but it still doesnt help!! i usually encounter 2 freezes in the game. for the first few matches, everything is fine and then then after a few rounds i start freezing. the freezing starts about 2-5 min and i cant do anything except either hard reset or use windowed version to use task manager. its been happening since last year after patch 8.1. its been months and riot still doesnt do anything. i also get more than 5 leaverbusters a week because of this and its really pissing me off. please dont ignore. With this much leaverbuster, im really afraid ill get ban even though i spent alot