Ryzen and Threadripper are CPUs, not hard drives, and they use completely different sockets, so you cannot use Ryzen in an X399 board and vice versa.
I should put this another way.
I have a M2 ssd drive in my Ryzen 7 1800 . X370 Bios etc
I just ordered a X399 Board for a new build with Thread Ripper CPU.
Would I be able to just plug my present M2 ssd Windows installed on a X370 motherboard drive ------>> into the new X399 Thread Ripper motherboard ?
Just proceed with normal set up routines without having to reinstall Windows?
Any down the road problems ?
I would recommend you to use Windows 10's "Reset PC" to prevent any problems.