(In reply to Jan Ziak from comment #6)
> (In reply to Alex Deucher from comment #3)
> > Please attach your xorg log and dmesg output.
> 
> Upstream Linux kernel does not support variable mclk on R9 390. I enabled
> variable mclk by patching some code in drivers/gpu/drm/amd/amdgpu/ (mostly
> ci_dpm.c).

What patch(es) did you use?

> 
> dmesg output contains some logging messages I added to my copy of Linux
> kernel source code.
> 
> > What resolution and refresh rate are you using on your monitor?
> 
> 1920x1080 60Hz
> 
> > Also are you using radeon or amdgpu?
> 
> Currently amdgpu.ko, radeon.ko in the past.