Microsoft basically uses the hardware that you put in your computer (especially CPU's) to determine which account is coupled to a valid windows license... So whenever you change hardware (especially CPU or motherboard) if im not mistaken microsoft can invalidate your windows key, which is a complete shit solution that microsoft has made for people that have to for example do benchmarking...
I am not allowed grey market software licenses because they somewhat break the EULA from microsoft... But I would go with those since they are 100 times cheaper IMO, anyway (especially when switching hardware)... Don't use grey market software licenses... HEHE.
