Blame the software first, then blame the hardware. Try downloading and installing the latest VIA 4-in-1 drivers to see if they fix the crashing and rebooting. I was getting memory dumps with my Asus A7V and windows 2000 service pack three fixed that. So make sure you have the latest service pack installed as well. You might also look for flash bios updates for the board. If you still have problems, then try a different fan. If it doesn't help, try a different power cord then try a different AC outlet. If none of those have any effect, then try a different power supply. If that fails, then it's probably a system board or processor problem.
I said to check for an update for the flash bios because the board you have is still failry new and might still have some issues with the bios; possibly with voltage settings and so forth.