My friend has called me to check out his computer...it happened after he has hoovered inside his case, even removing CPU fan to clean it throughly! I noticed that one of wires (that wire is purple) from PSU to motherboard was struck between CPU fan and heatsink! 
So I unscrewed CPU fan and loosen wire off and there is a mark on wire but no visible of metal wiring so it seemed ok.
When I press power button, the power lights come on as usual including CD/DVD drives but no screen...and then, all lights come off, not even power led but the fans are still whirring.
I can't quite point to the source of problem but I must be thinking it could be motherboard? I checked the voltage on power cable supplying to drives, they seemed ok.
If CPU was damaged, surely it won't stop BIOS displaying on screen?
So I unscrewed CPU fan and loosen wire off and there is a mark on wire but no visible of metal wiring so it seemed ok.When I press power button, the power lights come on as usual including CD/DVD drives but no screen...and then, all lights come off, not even power led but the fans are still whirring.
I can't quite point to the source of problem but I must be thinking it could be motherboard? I checked the voltage on power cable supplying to drives, they seemed ok.
If CPU was damaged, surely it won't stop BIOS displaying on screen?
