That's right, drivers were updated.
Took machine to the local shop, tech tested CPU on known good motherboard, and same problem happened. It seems like the culprit is the cpu's gpu chip. It's weird, though, that only the graphic part of the CPU is damaged.
Now, I'm thinking my old mobo might not be bad after all, would have to test myself, can't fully trust local "techs". Anyway, thanks for your help, this thread can now be tagged as solved.