I obtained a Mac Professional 4,1 and checked the serial quantity with About This Mac. It would not present a serial quantity. I’ve by no means seen this earlier than on a Mac Professional. Does anybody have any concept what this would possibly imply? I’d be all in favour of studying extra about serial numbers on motherboards, which apparently match the serial quantity showing on the case. Is there something that must be completed (for authorized causes or in any other case) when changing the motherboard? When that’s completed, the serial quantity on the case will, in fact, not match the serial quantity that comes up in About This Mac.