https://bugs.freedesktop.org/show_bug.cgi?id=93826
--- Comment #46 from Jonas jojonintendo@tutanota.com --- Same here with my XFX R9 390, latest Arch Linux and amdgpu driver. Forcing "high" power profile makes it work, but it also raises the temps (and probably power draw) too much to my liking.
If we could only up the vram frequency but not the core, maybe it would be a more acceptable situation of temps/features.