if the power supply was overvolting the chances are the computer is fried in some way and needs repairing.it wont take very long to kill one at 12 volts.
but,thats not always the case.so dont worry too much.
you would run the power supply under a dummy load on the 5 volts line for a about 20 minutes using a car brake light is the simplest method i can think of at the moment.
and simply monitor the voltage with your meter set to dc volts,if it cuts out or starts to rise you have problems.
i dont normally bother with the 9 volt rail as its tapped direct from the transformer as ac.
dont use the computer as a load when testing, its a bad expensive mistake bud.
but,thats not always the case.so dont worry too much.
you would run the power supply under a dummy load on the 5 volts line for a about 20 minutes using a car brake light is the simplest method i can think of at the moment.
and simply monitor the voltage with your meter set to dc volts,if it cuts out or starts to rise you have problems.
i dont normally bother with the 9 volt rail as its tapped direct from the transformer as ac.
dont use the computer as a load when testing, its a bad expensive mistake bud.