Hello all, have an older G4 desktop that starts, boots up, then 5-15 seconds later just dies. After this I have to wait about 1/2 hour until it can be restarted again but again 5-15 seconds and goes down. Did reset EPROM, didn

Have you checked all the air paths inside to insure they are clean? That includes air vent on the power supply. The fact that it runs for up to 15 seconds may me think heat. My power supply is shot and it does not start at all.

One of the major air intakes is just above the lower "handle" that acts as a foot:

It is not the four fancy vents that clog--it is the perforated section of the main case behind the vent holes. My G4 MDD gets filthy there.

The power supply has its own fans so check both ends of the PS for clogging.

Hello,

It sounds like your Macintosh’s power supply has failed and would need to be replaced.