Black screen of death

I was playing a game and about 7 mins in I got a black screen which resulted in me getting a "critical error" and the middle of a ranked game and resulting in my whole pc freezing and me being unable to get off the black screen, I couldn't even alt tab out to retry getting into the lobby or even run a crash dump since my whole pc froze. After forcing a shutdown and restarting I tried to rejoin and the same issue happened when loading in.another critical error with a freeze after patching the installer. What is this issue and why did it cost me LP as it has happened before