New
#11
Replacing the motherboard even with the exact same model motherboard will not allow you reactivate Windows.
Microsoft will consider this a different machine.
This is because part of the hardware signature that Windows activation calculates is derived from data stored in the motherboards BIOS EEPROM.
This part of the BIOS is installed when the motherboard is manufactured, and isn't intended to be modified by the user.
Even when you update the BIOS with the files provided by the manufacturer, this data is not modified (or contained in those files!).
This is somewhat similar to how WIndows 7 activation used the SLIC entry in the ACPI table for OEM activation, but due to exploitation, they stopped this activation method at Windows 8.
(It's a very simple process to embed a SLIC entry for any OEM into the BIOS, and then using that OEM's certificate and Serial, obtain a fully activated version of WIndows 7, which is completely undetectable to Microsoft...)
You can however use a perfect BIOS dump from your original activated motherboard, and write it to the new motherboard, if they the same exact model and revision, and are identical in every way other than serial number. This would effectively clone the board.
This isn't illegal, and since Windows 10 activation is automatic, and cannot be renounced, cannot be considered illegal in a strictly legal sense. Ethically it is dishonest though.