[firefly]

I have a G4 Quicksilver dual 800 that is shutting down by itself, for example, it powers on and then 5 seconds later powers off. Sometimes it stays on long enough to boot up. It was very infrequent at first, now it's all the time.

Do you agree that I need to replace the PSU?

[BigBadBiologist]

Most likely, it's the power supply. It could theoretically also be the CPU overheating; you could check to make sure your fans are clean and that your heatsink is making good contact with the CPUs.

[wubrew]

Originally Posted by firefly 

I have a G4 Quicksilver dual 800 that is shutting down by itself, for example, it powers on and then 5 seconds later powers off. Sometimes it stays on long enough to boot up. It was very infrequent at first, now it's all the time.

Do you agree that I need to replace the PSU?

Did you add or remove any HW recently?