Why SATA RAID does NOT work with an OS drive as NVME?

So I'm doing a SATA RAID 0 (for data only) on my system, but I can't install the RAID drivers because the OS drive is on an NVME drive. Why does the OS drive matter??

For now, i'm doing a software raid as that is my only solution.

Specs:

Ryzen 7 1700X
Asus Crosshair 6 VI Hero
RAID 0 includes, Samsung 840 Pro 128GB, Sandisk 120GB
 
Solution
You can install the OS on a single drive with the SATA controller set to RAID. Nothing special needs to be done as you can have a single drive in RAID. Be sure the M.2 drive is the only drive connected when installing the OS.