Hello! So a while ago I built a Media PC and installed windows 8.1 then upgraded to 10, it worked fine until I switched out the CPU and Motherboard, it still boots fine, as I went from an E7400 to E8400 (Using Old Parts). Anyways. it booted fine but now I have an Activate Windows Notification, I tried re-entering the key but it said it wasn't valid, any ideas? P.S. I got the key from my uncle who got it from his work as a programmer at PG&E (or some big power company).