Thanks again for your reply. I agree, I also prefer to have the latest firmware, and usually take the risk of upgrading, crossing fingers that the process will complete successfully, and the electricity won't be shut down in the middle
Turns out that the closest service provider is pretty far away from my place, my warranty assumes I take all expenses on shipment, and they will indeed reformat all drives before attempting to diagnose the problem. And if they don't find any issues, I'll be charged for the time spent with my PC. Given the problem is not an easy one to reproduce, I'm not willing to take this risk. I'll just buy a new mainboard instead, hoping it's the MB which causes BSODs, and not the CPU. I was told that pre-installed Vista won't work with the new mainboard, so I'll probably have to buy a Vista license as well.
Instead of getting exactly the same mainboard (I think it's nForce 650i), I'm willing to try something else. Do you think it'll worth it installing nForce 780i SLI and 1066 MHz memory? I have a Q6600 CPU.