My guess would be that one or more of the capacitors in the power supply are failing (bulging/leaking
), which basically means that the supply is defective. Power supplies are the most failure prone component in a PC, so this is not unusual. However, the motherboard also has capacitors which can be prone to this type of problem as well. I would first open the system and inspect the motherboard to see if any of the capacitors are bulging or leaking. If so, then you can stop right there as it probably won't be worth while replacing the motherboard in a 9 year old system.
If the motherboard looks OK then you could try testing the voltage from the power supply (using a meter as shown in my book) to see if it is within the proper specifications. If not, then the power supply should be replaced. But if it is within voltage specifications it can still be bad. In that case the only way to know for sure is to replace the power supply with a known-good spare (as a test). If that works then that would confirm that the original supply is defective. In that case you could either leave the spare installed or purchase a new replacement power supply.
You can see my power supply recommendation criteria here
. I currently recommend both PC Power & Cooling
power supplies. Both of those companies feature high quality single-rail designs
which are primarly manufactured by Seasonic
. Let me know how the testing and/or replacement turns out, Scott.
PS: Thanks for the kind words about my book, and welcome to the forum!