Huh, and I was worrying that's just my GPU overheating.
Anything's possible, I guess. Maybe I need to keep staring at CoreTemp and GPU-Z, whether the CPU and/or GPU temperatures seem abnormally high. Currently they don't, the max where any CPU core has visited e.g. during this session is 50 Celsius, and for the GPU 60 Celsius degrees (and now they are considerably below that).
Also normally if the system temperature gets higher, the system reacts by spinning the fan faster, which you can hear the easiest when you play some graphically heavy game. That doesn't happen in this case.
Anyways, these occasional problems started after I updated to the latest NVidia drivers (320.18), so if they persist. maybe I indeed downgrade to some older drivers and see if I still face any issues. Especially if that brings the compatibility back to a couple of older games, as it has been reported elsewhere too that these 320.x NVidia drivers cause backwards compatibility problems to some older Windows games.
I had a bit similar (but worse) problems on my work PC. They disappeared after I updated to the newest graphics drivers. That also lead me to believe this is at least somehow related to graphics drivers, also as the drivers sometimes crash altogether on their own.
I can't speak for you, of course, but this has happened to me twice, and both times it was the motherboard reaching critical mass.
EDIT: And yes, this didn't affect gaming as far as I remember. Fuck knows why. It did make launching a game pretty arduous, though.
What does "reaching critical mass" mean?
No problems launching games here, fortunately. :)