Unfortunately the new ucode (hawaii_k_smc.bin) file doesn't work for me. I don't know if it does matter but as I tried to install a Hackintosh system recently I expericenced EXACTLY the same symptom(black screen, unresponsive system) after a couple of minutes. One could argue that it's a complete different setup but it is the fact that if I disable the GraphicsEnabler then the black screen issue vanishes. So maybe one can assume that the dpm (via hardware) is corrupt. Is it possible to try (experimentally) the new amdgpu-pro driver for r9 390 on Ubuntu 16.04? Or can we expect to receive the same issue as the all-open stack, either way?