Motherboard or CPU or both?

[ArmandoRuiz]

Hi everyone,
I had just replaced my old mobo, processor and system memory, the old one was having the same problem I have right now...
Well, the system worked fine for about a week, installed OS windows XP Pro updated completely, the CPU is a P4 3.0 800 FSB, then two days ago turned it on and the keyboard didn't respond though,the computer booted up, i got to the windows log-in screen. Well, I remove the case from the cabinet, opened it up to check connections, closed back and reconnect, when I try to turn it on, it didn't. Now I replaced the case with a bigger power supply and all i got now is the fan from the power supply, the fan from the CPU and the chasis fan working, when I plug in the power. The computer's power hasn't been pushed yet, I havent yet push it to turn the computer on. And, when i do nothing happens though.
So, I suspect, I kind of wish that the probelm resides in the mobo...
Any suggestions what the problem might be?

Thanks in advance...

 

[RealBlackStuff]

After changing the PSU, did you connect that square 4-pin cable from PSU to motherboard again?

 

[ArmandoRuiz]

Yes, I pluged that in... what's weird is that right after I plug in the power to the PSU, is that the fans start working; but when I try to start the computer it doesn't start nothing happens...

 

[Peerob]

My guess is you have wrongly connected the power switch. It is easily doen - I did it last week.

 

[ArmandoRuiz]

Thanks again folks... this is a rebuilt for an old computer that stoped working, and it is also my first build (you can say)..So because it is stressing for me to deal with this and I'm getting anxious to get my (new rebuilt system) I have taken it to a shop, they will try to figure it out...and I guess I will have to rebuild again...But then again thanks for your time and support. I will come back here in the future If I have any more problems....
Thanks again...