Terrific; many thanks! Almost there. Two main questions left:
1. I assume the big advantage of using a logic board from a Mac Mini is to guarantee that it will fit in the G4 case. But, that will almost certainly lead to a cobbled-together arrangement, with loose wires/cables running through empty slots/holes in the back of the case. Is there any place where I can find reliable dimensions and photographs, showing the sizes and arrangements of any "full size" logic boards, in the hope that I might find a full-size board that will be at least moderately compatible with my G4 Quicksilver case?
2. I also assume that a "logic board" does not include the actual CPU. If I buy a standard Intel i5 CPU, will that be compatible with a standard Apple logic board designed to hold an i5? Or, is there any special class/series/label of i5 processors that I need to focus upon? Now, I'm aware of various factors, such as bus speeds, etc, which will be printed on the CPU box. Clearly, those will need to be compatible. The Q is whether a standard i5 will work with a standard Apple board, assuming that the operating parameters are within compatible ranges.