Setup a Microsoft Account and link your current PC to it , then backup whatever you want to save and perform a clean install on your new setup and activate it with your Microsoft account from within windows. Skip the key entry during setup and activate it from within windows with the registered Microsoft Account.
https://www.microsoft.com/en-us/software-download/windows10/
Create a USB installer here ^
[video="https://www.youtube.com/watch?v=FP4sAhmH_Oo"][/video]
[video="https://www.youtube.com/watch?v=u4ROoOkPWIM"][/video]