Power Supply or M/b problem?

[Gumby16]

I'm running an ASUS A7V m/b with 256 MB RAM. Lately, the computer has been shutting off randomly anywhere between 10 minutes and 5 hours. I've used the ASUS Probe diagnostic program and I've been getting small fluctuations in the +12V line. The last time I turned it on, it wouldn't boot at all and began to smell burnt after about 30 seconds. There's no exterior damage to the chip. My bet is on the power supply being bad. Anyone have any suggestions what else it may be? Could there be a m/b problem with a bad capacitor or something? Any guesses are welcome!

 

[Operandi]

Sounds like classic power supply failure to me.