(Solution posted at bottom of post)
As of earlier this week, playing Overwatch 2 would cause my computer to shut down. It couldn’t be booted back up again until I flip the power switch off, wait a couple of seconds, then flip it back on again. At its worst, I couldn’t even finish a longer game before the computer would shut down.
I could play the entirety of launch week without issues; this problem started happening on Thursday, October 13th. I know this is a known issue mentioned in this tweet: https://twitter.com/BlizzardCSEU_EN/status/1580166393705959424
I’ve checked the systems, and no hardware is maxed out, no memory leaks, there are no bottle necks, the computer is free of dust, and it only happens when I’m playing Overwatch 2.
Specs:
- GTX 1080 (516.94)
- Ryzen 5 5600K (Standard clocked)
- 16GB DDR4
- Windows 10 21H1, 19042.2130
What fixed it for me:
I managed to fix the issue by updating my graphics drivers to the latest version (522.25). I’ve currently played 7 games in a row with no issues whatsoever.
EDIT: Never mind, my computer just shut down again after 4 games this morning. 
EDIT2: I downclocked my GPU somewhat (like 10%), and set a framerate cap in-game to 60, which seem to have worked. Haven’t had a shutdown in about two days now.