I have an own build PC which has been running fine for 18 months, yesterday whilst playing a game, it just shut down and wont power back up. The PSU tested okay and there is power going to the mother board but the fan for Processor isnt turning.
Many motherboards today auto-shutdown the system if the CPU fan fails. This is to protect the CPU from what would otherwise be catastrophic disaster. Take a look at your motherboard manual, to see if it says anything about this facility.
So my advice would be, check and if necessary replace the fan first, and then see if you still have a problem.
Fans can be purchased separately from places such as Maplin Electronics.
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