I support a bunch of these 8900's at work. They can be very temperamental machines. Chances are the board is not dead, just acting like it. Pull the CMOS battery unplug and wait half an hour. Also, try just 1 stick of ram to force a re-learn for memory.

Edit: about 1/3 of my machines have the exact same problem after a power-outage. I haven't had one fail to come back from the grave.