Question PC only boots after mains plug removed and reinserted - the gets stck

[Denis AB]

My PC is an HP 9400 workstation that's just started misbehaving. Will only start when mains turned off then on, and comes on immediately. All fans start, but nothing else happens and screen stays black. I then turn off by depressing power switch, but won't switch back on however long I wait, and I have to do the mains thing again, with exactly the same results as already described. I've changed BIOS battery, and old one was dead, and reset BIOS at the motherboard switch, but this hasn't made any difference. Any ideas what my problem is. Denis

 

[Lutfij]

How old is the prebuilt? Can you parse an SKU to the workstation to learn of the specs of the prebuilt? It's possible that the PSU has given up the ghost and would need replacing, that is, ofc after we learn of the age of the system and it's PSU.

 

[Denis AB]

No idea how to do that, I'm afraid. PC case has inspection stamp dated 5/2007, and PSU is a Delta Electronics 800w unit. Surely, if PSU was kaput, 4 fans and hard drive wouldn't be working? Denis