Users who run a Microsoft Original Equipment Manufacturer (OEM) operating system may upgrade or replace most of the hardware components on the computer and still maintain the license for the original Microsoft OEM operating system software provided by the OEM, with the exception of an upgrade or a replacement of the motherboard. An upgrade or a replacement of the motherboard is considered to create a new personal computer. Therefore, Microsoft OEM operating system software cannot be transferred from another computer. If the motherboard is upgraded or replaced for reasons other than a defect then a new computer is created, and a new operating system license is required. If the motherboard is replaced because of a defect, the user does not need to acquire a new operating system license for the computer. The motherboard replacement must be the same make and model, or the same manufacturer’s replacement or equivalent, as defined by that manufacturer’s warranty. The reason for this licensing rule primarily relates to the end-user license agreement (EULA) and the support of the software covered by that EULA. The EULA is a set of usage rights granted to the end-user by the computer manufacturer. The EULA relates only to rights for that software as installed on that particular computer. The System Builder is required to support the software on that individual computer.
Understanding that end-users, over time, upgrade their computers with different components, Microsoft views the CPU as the one remaining base component that still defines that original computer. Because the motherboard contains the CPU, when the motherboard is replaced for reasons other than defect, a new computer is essentially created. Therefore, the original OEM cannot be expected to support this new computer that they did not manufacture.