I use an MSI R9 390, the card is famously unoptimized and needs GRUB edits for injection of kernel arguments radeon.cik_support=0 radeon.si_support=0 amdgpu.cik_support=1 amdgpu.si_support=1 amdgpu.dpm=1 amdgpu.dc=1
to work correctly with AMDGPU open source drivers, this worked fine in Beta 1-2, but when clean installing to the newest full release it seems to not change anything after sudo update-grub
since the usual behaviour of the patch being missing takes place (black screen and monitor disconnection after or during password greeting screen)
It's been installed on a baremetal GPT layout 256gb SSD, CPU is an FX-8350