Unrecognized device in Alienware Graphics Amplifier

Hi,

I just bought a radeon 390x to replace my GTX 760.

The GTX 760 in the AGA works ok, but after replacing it with my new 390x, I got this error message at boot:

"Unrecognized device in Alienware Graphics Amplifier. Alienware Graphics Amplifier supports NVIDIA or AMD Graphics cards only. Press any key to continue..."

When I press any key, I boot fine, but then AGA tells me something about it being connected and that I need to reboot, following the instruction, I'm back at staring at the error message above again.

390x is marked as compatible according to the FAQ.

I have also followed the AMD download and instruction to install the AGA driver. But still no luck,

Device: Alienware 15r2, i7-6700HQ, 32GB, 970m

OS: Windows 10 Enterprise

What am I missing? Why is this so hard?