I just installed a NVMe drive on an adapter in my ASUS Sabertooth 990FX R2.0 based system. The BIOS is the latest version 2901 from 2016. The drive is a clone of my existing system.
The drive is recognize, bootable and seems to reach reasonable performance considering the config. The only problem is that the system will not boot directly on the drive no matter which setting I put in the BIOS.

I open the BIOS, set the drive as the first (and only) priority for storage drive.
When I reboot, the system tells me to insert a bootable drive.
I open the BIOS again and there, the storage drive is set to "PATA SM" which has no drive listed. The NVMe drive is listed below.
It is as if at boot time the system had not detected/initialize the drive yet and only does it after.

To boot the system, I am forced to open the BIOS and manually select the drive. How could I set the BIOS to make sure it boots using the NVMe drive? Thank you all.