No Power on self test

I have recently upgraded my machine, and thought it would be a nice idea to use all my older bits as hand me downs, and build the wife a faster computer. However, i have built it all up, and now the machine wont power up at all. Checked every aspect of the machine, took bits out replaced with other bits. hit the power button again, powers up perfect. Then when you shut machine down, and try restarting again, it is dead again. I thought bugger it i will put all of her old stuff back in her case and let he keep her exsisting PC, which is Atlhlon axia with 512mb of 133 ram.
I installed everything back into her case. as before.
Turned the power on. All fans come on, harddrives spin up, CPU fan spins up, but no display on monitor, and no post beep.

Reset the bios, and then changed settings in bios to be able to install windows back on this machine from cd-rom, saved settings, and restarted. back to the no display, and no post. Reset bios again, and still nothing.

Any idea's what could be the problem. I spent like 4 hours on this last night, and ended up walking away from it at like 1am thins morning.
The wife is gonna kill me now, as she had a perfectly good working PC, until i started mucking around with it lol.

Any help would be much appreciated..

Was just thinking while at work.

Could it be the battery at all.
I mean when you reset the bios on the Abit board, it then posts upon next reboot. it boots directly into bios. then you hit save and restart and it cannot restart again.. ??

It could be low PSU voltages. Got a volt meter and a paperclip? In reference to the new machine, of course.

(The paperclip is for tricking the PSU into turning itself on without a mobo, btw.)

Old machine... swap BIOS batteries with the new machine and see if that changes anything.

The battery is not going to make a bit of difference. When the battery no longer works, you get prompted to go into the BIOS to verify hardware.

I like the idea of the Power Supply. Maybe that's bad. Try a different one and see what happens.

Could also be the MB. Do you have a way to test the other 'bits' in another machine?

Also, when working on this, try only using the MB, CPU, RAM, and video card. Perhaps swap them out with known working replacements one at a time. This may identify a bad part.

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