I am preparing to service the pc that I suspect has a PSU issue. The reason I suspect this is because the pc only stays on a couple minutes after power up, then it abruptly shuts down. This pc has been built by me and has been running for two years with windows xp. The user only uses this pc once or twice a week, doesn't download anything except microsoft and norton antivirus updates. No problems till this weekend. Now it just shuts down after being up about 3 minutes.
According to other posts that it is possible that a faulty psu can cause other issues on the pc like the mobo etc. How do you know if there was any damage to the other components. If they run after I exchange the psu, can I assume everything will be ok?

If you're not sure if the PSU is blown I would take a good whiff of the back of the psu when it's running just to see if anything smells funky and maybe the same for the inside of the case.

Then I would jump start the psu and check the volts w/ a meter and see if it can stay on for a good amount of time running the hdd/dvd/fans w/o the mobo.

If all is well continue to the bare bones test and carefully check the volts under load and try the beep code test. If you don't get any codes it could be the mobo.