It crashed again, I rebooted, it got to the login screen, and I typed nearly 6 letters of my password before it crashed again. Uh oh
So I have reason to suspect the case is fucky (grounding problems with the USB), and this feels like either a motherboard or cpu problem.
The cpu is like 5 years old, the motherboard only 2.
Could also, in theory, be ram?
So I'll need to memtest it, and also try watching the temperatures while it runs. I've never had cooling problems before, but the way it kept getting worse when I rebooted it smells like cooling.
@foone I had literally this exact problem and it was a failing cooling system. Once I replaced the water cooler unit, everything worked again
@mia this is a water cooled system but the temperatures didn't look that bad when I checked them. I'll have to look more into that