Pop in the old board and drive....

And it works! So the PAV board IS GOOD.

New board, old drive:

No good. Light by the data port for the HDD and CD Drive turns on.

I also took the opportunity to test the 500MHz board I had laying around and it works as well, though the power light stays amber. It booted OS 9, so I'm happy.

I put the old drive back in. I'll try removing the Tiger disk by clicking the mouse at startup and try booting my Japanese OS 9 disk.

EDIT: So far so good. Got the Tiger disk out and started installing OS 9.2. I put the Firmware update on a floppy disk since it won't pick up my USB drive :-/ Luckily my USB floppy drive comes with a disk that has the drivers for OS 8 and 9

EDITEDIT: Darn thing died in the middle of installing OS 9 I can't tell if it finished the install or not.... It won't start now. Guess both the 600MHz and 500MHz boards are bad. That, or it overheated somehow. The iMac was pretty darn warm in the back. I have a fan pointed at it now so it'll cool better. I'll try starting it again in about 30 minutes. If it doesn't start, then I'll just switch back to the 400MHz board.