redsnail,
It could be something as simple as one of the RAILs in the Power Supply has failed. It could be the Power Supply failed due to the computer being under powered.
You might end up replacing the Power Supply and the computer will still have the same problems. That just means your system has more than one problem.
When people are running under powered, I tell them that their Power Supply is a problem, but it might not be the
ONLY problem.
Take Care,
Richard
P.S. Lets hope the second problem is not the motherboard itself.