One of the shortcomings of AMD’s X399 ThreadRipper HEDT platform was that it lacked NVMe RAID support. You did have the ability to build soft-RAID arrays using NVMe drives, you were not able to boot from them. It looks like AMD will be remedying this by adding support for NVMe RAID through a software update, which is scheduled for September 25th.
The update will come in the form of both a driver update (including a lightweight F6-install driver), and a motherboard BIOS update. This will enable X399 motherboards to boot from RAID 0, RAID 1, and RAID 10 arrays that are made up of ten NVMe drives. AMD said they have no plans to bring NVMe RAID support for the X370 or B350 platforms.