Screen freeze in-game

Recentrly I've been having this problem when I'm playing, suddenly my screen freezes randomly. This stay's the same for mostly about 2-3 minutes. After that i see the in-game reconnect bar and when I'm back connected I can play fine. The moments it freezes are very random, sometimes I can play 5 games without any problems. Other games I have it twice in 1 game. Also when it freezes, I cant do anything else on my pc, I have no sounds at all. It's really annoying, because when my screen freezes, my champion walks back to base (because I'm disconnected) and it usually results in me dying.

I have a new pc since march, never had this problem on my previous one. I have a prety powerful pc, I play LOL with 100fps+ on max settings, play other games without any problems.

Anyone any thoughts?