Common causes are:
1. Aging parts.
2. Heat.
3. Overtaxed power supplies (hint: item 1 leads to this.)
Bob
We have 2 mystery PC desktops that turn on and off randomly. What could be causing this?
They were assembled from parts:
Titan P4 mobo for Prescott (P4) CPU GA-8IG1000 Series apparently with built-in Video, Maxtor 80GB, 512 MB RAM (on DDR1), Powerman power supply probably around 235-300 Watt), Celeron 2.26 ghz

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