i worked on a compaq recently that did the same thing.
it didn't like having a second cdrom(burner).
it worked fine with either drive but as soon as i put both in it would
power on for half a second then shut down.
i decided to leave out the cdrom and it worked fine.
have you tried it with just the floppy connected to see if it posts?

yhan wrote:
hi,
i connected two hard disks in the supply.