Your motherboard supports a specific form of software raid that it expects windows to respect (with a driver iirc).
Basically that bios setting will enable it to “boot from the software raid”, then once you get to the operating system it needs to understand how to handle the software raid and make it a proper volume.
This made sense in the before-times with windows and booting from spinning disks (well, not really but still), but now you’re better off making a proper software raid yourself.
Your chipset doesn’t have a proper hardware raid controller (actually it probably has most of one by now, just not the iop itself, basically like a small cpu core that figures out what to do next), so it’s not proper hardware raid, just software games to let your cpu do software raid.
If you’re running Linux just use lvm, it’s fast and you’ll be pretty happy with the results.