@Ima
I am pretty sure, as may people suggest, excessive current loading is the problem. If you are so inclined, I would suggest attempting to locate any other places you might be able to feed power into the motherboard in addition to the normal connector.
On an A1200 this is easy since you have the floppy power point, but I expect an A4K mobo is trickier.
Has anybody managed to add an additional power feed to an A4K motherboard?
