I have a 486 that died in similar ways. On rebooting it would get about half-way through the BIOS message and stop. Turned out the power supply fan had died, taking the PS with it. I replaced it with a PC Power and Cooling supply and it's been happy ever since.

It sounds like you have a power problem.

So then after doing a bit of web research I see a post describing my symptoms to a "T", and that a possible solution is that my power supply isn't hefty enough... so I go and buy a 400 watt power supply. Still no luck.

Specific symptoms:

- when power is turned on, sometimes the fans will not run.
- when power is turned on, even if the fans do run, machine will not bootstrap BIOS, will not power up hard drives.

ATX power supplies get signals from the motherboard. The won't turn on if the motherboard isn't supplying the right signals. As I understand it.

It used to be that AMD recommended specific power supplies. But they don't any more. Any "ATX 12V" supply should be fine for an Athlon these days.

Go back to basics.

1) Is the new PS you bought any good? I don't know how you can diagnose it without having it work in a PC. :-(

2) Install the motherboard with no cards at all. Does the PS run properly? Do the LEDs on the motherboard light properly? Does the motherboard cause the proper beeps through the system speaker?

If you can't get it to act right without anything installed, then either the new MB or new PS or both have problems.

After those work OK, plug in the video card and other cards sequentially after you verify the simpler configuration works.

HTH a bit. Best of luck.

Cheers,
Scott.