If you have to talk with MS to get the OS to work, since you had a motherboard failure you should tell them that it failed and you had to install a new motherboard.
If the new motherboard is similar enough to the old motherboard then it might work, and eventually change out any drivers that it needs. If there is too much difference in motherboards it might not even boot. I've not had too much trouble doing this with much older versions of Windows but haven't needed to do it recently.