I'm working with HP Pavilion 552x with OS XP. I had to buy a new PSU and it seems to be working fine. But when i start the computer all fans work but nothing else does. It doesn't recognize the monitor, had drive and CD drive or the floppy. It's basically dead! I visibly can't see anything out of sorts with the caps on the mother board a P4S-LA. And I pulled out the CPU to make sure it was set properly. When I turn on the computer I am unable to shut it down by holding the button in for 5 seconds (I held it longer) the only way to shut down is by the button on the PSU. I am dumb founded and in need of some real good help.