The Main Logic Board is a possible culpit, but I'd wager it isn't the cause of the problem. As others have suggested, the battery is possibly the issue, and it is easy to remove, test and replace. The power supply could also be faulty. As could the CPU's and the RAM. I'd start with checking the battery, then testing the RAM. You didn't mention the start-up chime. Has it changed? Dave -- Windows (WIHN-doze), n. - A 32-bit extension and graphical shell to a 16-bit patch to an 8-bit operating system originally coded for a 4-bit processor built by a 2-bit company that couldn't stand 1-bit of competition. On 30-May-08, at 09:29, Paul Moortgat wrote: > The G5 is 3.5 year old. In my opinion it can be two things. The > motherboard is gone, or not so obvious, the battery is empty. Can > it be that the battery is out of order? > And will the G5 no longer work with a broken or empty battery?