I disagree ... older PCs are much less tolerant to changes to the input voltage. A "simulated brown-out" might kill it completely. Electrolytic capacitors are

I disagree ... older PCs are much less tolerant to changes to the input voltage. A "simulated brown-out" might kill it completely. Electrolytic capacitors are probably to blame for the smoke - they definitely fail with age. The good news is that you can probably replace them since everything was through-hole back then (as opposed to surface mount).