The motherboard is ECS 848P-A. Recently it's been booting but shutting down on its own. Now it won't boot at all, from floppy, system DVD or boot thumb drive. POST works every time. DVD drive spins up, then quits after beginning setup.
I've been through BIOS settings many times, including resetting to defaults and specifying boot from system drive and playing with boot sequences.
I've removed all unnecessary hardware and PCI cards, swapped several memory modules, the video card, DVD drive and power supply, tried running the setup DVD to an alternate HDD. I'm not sure what's left other than a different board or CPU.