So I have a friend who wants to upgrade his computer, but he's gonna re-use his CPU and HDD. My question is, if he buys a new motherboard will he have to re-buy windows? He currently has windows 8.1. His current computer is https://support.hp.com/gb-en/document/c04701774 I assume since it's a pre-built HP potato the windows will be bound to the motherboard.