PC Freezes when you playing a game in league solution.

Hello i had a problem with my custom computer when ever i play a game in league like in 10 or 20 min in the game it will freezes my whole computer, so i first thought it might be my computer that could be messed up so i dust it and clean it and it will still freeze , so what i did is factory reset my whole computer and then i reinstalled league and i had no problems with the freeze hope this helps u guys but remember back your files :^).