When installing a new motherboard, reinstall the operating system as required.
When installing a new motherboard, reinstall the operating system as required.
You may not need to reinstall Windows, but it will remain unactivated.
Occasionally it isn't, but it's wise to reinstall nonetheless.
It varies. Usually, more than just a hardware swap is needed to trigger a Windows shutdown. I changed my motherboard, but the one I had ordered was still available. Windows didn’t seem to mind much. Still, I’d remove any motherboard-related programs and drivers first—such as audio, Wi-Fi, and control software. After turning on the new board, reinstall those drivers.