constant freezing randomly

for my past couple games, my game will randomly freeze for like 5 seconds, then just be a black screen. sometime after about 15 to 30 seconds it will go back to the game, then freeze again 3 minutes later, or it wont unfreeze and i have to ctrl+alt+del, sign out, sign back in, open league and load back into the game (which takes about 3 to 7 minutes) only to find out that i am 30 cs down, and 4 levels down. please god fix this fucking bug its almost not even worth it to play while it is in the game...