No power

[TurboMike]

My mom called me about her Computer. She says she started to turn it on, the keyboard light would flicker... but nothing else. I figured Power Supply so I had it send it to me, replaced the supply... nothing. When you turn it on, keyboard light clickers once... sometimes the process fan will spin a revolution or so. Now I'm thinking motherboard.. any thoughts?

 

[Ike0069]

If you know the PSU is good, then it's most likely the MB. Remove it from the case and try again just to ensure it isn't shorting against anything.

 

[Ivan05]

IIRC, some of the XP mobos will shutdown almost immediately if the CPU fan doesn't spin up. The mobo senses the fan RPM's and shuts off if they're not high enough as a way of preventing overheating.

I'm not saying this is the cause of your problem, but don't want you to overlook the possibility.