Game randomly freezes between the 15-20 minute mark

I have searched around in the boards and it seems I suffer from the same issue, the game just randomly freezes at around the 15-20 minute mark but the music still plays and I can still alt tab, making me have to restart my PC, a process that can not only waste a lot of my time, but also cost me a match (which it just did) as all as give people I play with the impression I left the game and then I recieve unfair reports because of a simple, yet stupid, crash/freeze that happens outside of my control. Any other game I have on my PC works fine, with League being the only game I have that does this, I have an Nvidia GeForce GTX 860m, but this has never given me any issues, specially from games that demand more from the graphics card, I also have all of my drivers updated and have reinstalled the game recently, leading me to believe this problem is not on my end, but on the game's end, that there is something wrong with the game that is making it freeze me have to restart the PC. If this is the case (which I am almost certain it is) then please fix this, I can't imagine how many reports I've had because of this and it's getting frustrating.
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