I recently replaced an intermittent motherboard (MLB) in my 1.6GHz G5 Power Mac with a 1.8Ghz MLB. I plugged in the old 1.6GHz CPU into the 1.8GHz MLB, but unfortunately the computer does not work now. After a few seconds all the fans come on, and there is no video signal. I read that tis kind of a scale down should work. Has anyone done anything similar or advise me what to do? Any pointers would be greatly appreciated.