(In reply to Pavel Bordukov from comment #54)

> Doesn't work for me. Linux 4.11.3, R9 290x, Asus MG279Q, 144Hz has
> flickering and dirty picture. 120Hz works well.

I have a similar setup. Can you try what I posted above?

Make sure to raise the DC clock above the default value, e.g. to 625 MHz (value
62500)

If you use amdgpu: in amdgpu_atombios.c adev->clock.default_dispclk
If you use radeon: in atombios_crtc.c rdev->clock.default_dispclk

That should fix the broken image. To fix flickering, set mclk to high (echo 1 >
/sys/class/drm/card0/device/power_dpm_force_performance_level)