Is your motherboard toast? If your logic board has burned out, it's a sad thing, but you're going to have to replace it. See how to remove the logic board from the Power Mac desktop computer.
PowerBook Medic is the ultimate resource for Mac computers and electronics repair. They have helpful tutorials on most Apple products including the MacBook, MacBook Pro, PowerBook, iBook, iPhone, iPod, and more, covering topics from disassemblies, to RAM upgrades, to replacement hard drives.
Repair a Power Mac G5 - Remove the logic board
In this PowerBook Medic video tutorial, learn how to remove the logic board from a Power Mac G5 computer. This is just one of the steps for the teardown procedure of the Power Mac. Find more details on taking apart and repairing the Power Mac G5 (A1177) in the repair guide.