A recent support page and community update posting suggest that NVMe RAID support is coming to Threadripper and the X399 platform imminently (as soon as motherboard manufacturers release an updated BIOS/UEFI). AMD will support up to six NVMe drives without adapters in a RAID 0, 1, or 10 array with all the drives wired directly to the PCI-E controller in the CPU rather than being routed through the chipset (meaning no DMI bottlenecking). There are no limits on the brand of drives and the NVMe RAID update is free with no hardware or software keys needed to unlock it.
NVMe SSDs are very fast on their own, but when combined in a RAID array directly wired to the CPU things really get interesting. AMD claims that it saw read speeds of 21.2 GB/s when reading from six Samsung 960 Pro 512 GB drives in a RAID 0 array! The company also saw near perfect scaling with their test array (when adding up to six drives over a single drive) with reads scaling 6x on reads and 5.38x on writes. Intel's VROC seems to have the theoretical performance advantage here with the ability to RAID more total drives (four per VMD and three VMDs per CPU) but only after purchasing a hardware key and when using more than one VMD it can't be a bootable OS array. When it comes to bootable arrays, AMD would appear to have the upper hand with free support for up to six drives that can be used to run your bootable OS array! Windows has never booted faster! (heh)
Along with its partners releasing BIOS updates, AMD is releasing updates to its NVMe RAID Driver (version 17.50) and RAIDXpert2 Windows management ultility. Currently, Windows 10 x64 build 1703 is officially supported and fresh installs of Windows are recommended (and if you are currently running your Windows OS off of a RAID array a fresh install is required).
Once BIOS updates are available (and they are coming shortly), users will have to jump through a few hoops to get a NVMe RAID up and running, but those hoops may just be worth it for enthusiasts wanting the best storage performance! For one, if you have a RAID array (bootable or not) you will not be able to do an in-place upgrade. If you have a SATA RAID you must back up your data and break down the array before updating the UEFI/BIOS and installing the Windows driver. Further, if your existing array is bootable with your operating system installed on it you will need to back up your data, upgrade the BIOS, and perform a fresh install of Windows with the AMD supplied F6 driver. After upgrading the BIOS, there will be a new menu item (the exact name will vary by manufacturer but SATA Mode and SATA Configuration are likely suspects) where users will need to change the mode from SATA or AHCI to RAID.
Oh, and did I mention to back up your data before diving into this? NVMe RAID support for Threadripper is a long-awaited feature and has a lot of promise with Threadripper offering up 64 PCI-E lanes and, according to AMD, many boards offering 7 slots (6 with a graphics card) which is where AMD is getting the six drive support number. It is appears that using adapters like the Asus Hyper M.2 cards or DIMM.2 slots would allow users to go past that six drive limit though.
NVMe RAID support on X399 / Threadripper is a feature we are in the process of testing now (see comments) and I am very interested in what the results are! Stay tuned for more information as it develops!