p4 1.5 won't boot

[a0chicken]

It was working just fine last night, got XP installed and we were sitting in windows. It was with my power supply because the 250 watt PSU didn't have aux or p4 power conn.
So we buy an adapter (4 pin molex --> p4) and try it out with the 250.
Fans turn on, but no Beep, monitor doesn't turn on, and no HDD spin.
So we pop out a 480 generic and same thing happens.
So we try with my 460w Enermax (just shift ATX/P4 power from my mobo to the other comp because I just neatened my wires up) and it still won't boot.

I've tried a different video card because that's the only other thing I can really swap..

Any idea what's causing this?

Edit: P4 1.5, Chaintech 9BJA, 512 PC133, 40g HD.

[cirthix]

be more specific by " not boot" do you mean an os boot failure, crashes, missing system files, no post, etc... try resetting the bios. you can do this by unplugging the system and taking the battery on the motherboard out for a bit

[a0chicken]

It won't POST, the monitor won't come on, that's about all I can say.
I ran it out of the case on a mobo box so that ruled out short circuiting (was the problem on another computer I worked on).

[jjcom]

sounds odd, the Hds should spin up. What are the rails on the PSU?

jjcom

[a0chicken]

I'm not sure about the quality of the PSUs my dad has. One is a generic 250w, the other is an Okia 480w ( "480w" )
It's strange that these two won't run it, because I had a generic 350w running it for 3 years.

[jjcom]

Do you have a multimeter you could use, maybe the rails are very low. that would explain why the HDs weren't going

jjcom

[a0chicken]

I got it all figured out, it was the PSU. Picked up a new one and it's running agian.