[alxtr1bal]

Edit : Thank you @Milhouse

With the xorg.conf solution, i have as well the RX 460 working.
But i'm loosing the passtrough with the AVR. (tried all the #0915 series. I have normal audio on the interface though.

Setup :
RX460 HDMI (or DP) -> monitor.
Motherboard HDMI->AVR

Before (RX460 not working):
Motherboard HDMI (AMD GPU)->AVR->Monitor

lspci | pastebinit : http://sprunge.us/hZWY
lspci -v | pastebinit : http://sprunge.us/iOSg
dmesg | pastebinit : http://sprunge.us/OLaV
cat /var/log/Xorg.0.log | pastebinit : http://sprunge.us/XYRI

Edit : vdapuinfo : http://sprunge.us/hSJA