I am also having somewhat of the same problem. To answer your questions, AndyFair, I have checked the monitoring in the BIOS, and it is the same as the utility used in windows (asus probe). I'm around 13.44v running an AMD Athlon 2000+. This is on a spare computer, so i really don't do much gaming. However, I find that it will restart or freeze frequently. I even changed power supplies a few times, but it still does the same thing. Let me know if you have any more suggestions!
Thanks,
Matt