I started with a Windows 10 with a sata boot SSD and SATA second drive. I'm using an MSI z370m mortar board. I bought a new M2 nvme drive and put it in and installed Windows fresh on to that drive. I finished installing everything and when I boot I get the option of choosing disc 1 the old SSD or disk 6 the new M2 Drive. I was ready to get rid of my old SSD. In the BIOS I can see M2 listed as Samsung and SATA sad and hdd. But when I go to the boot order I can only see the SSD as an option to choose but not the M2 Drive. There is a listing of uefi hard disk as well. If I take the old SSD off the boot order than the machine does not do and it goes back into the BIOS. It's like it does not know how to boot off an M2 Drive, or somehow the drive is not marked as bootable. What is happening here? in the partition manager it is marked as boot page active crash dump primary partition I see somewhere else in the BIOS there is a Win10 WHQL authentication Settings (CSM/UEFI). I assume this is irrelevant. It's on csm. if I swap to the other one then it also doesn't boot and the old SSD is taken off the list of drives https://us.msi.com/support/technical_details/MB_BIOS_Manual Also my mouse used to work in the bios, and now it isn't?