New
#11
If you plan on having the OS on the new M.2 Nvme I would suggest disconnecting all other drives when installing, particularly the existing SSD with Windows on it. This would be important if you plan to clean install windows on the Nvme. You can connect and then delete the Windows partition on the old SSD after everything is set up.
If you plan on installing a clone/image of your system to the new Nvme then it would be best to have that image on an external storage device.
Disconnecting the existing system drive (and all other internal drives) will help to avoid many problems. Some folks here may have experience with installing and cloning an Nvme from a connected internal drive without problems. If they do I'm sure they will post something.