Comment # 113 on bug 76490 from Alex Deucher

(In reply to Daniel Exner from comment #112)
> If I read that correct R9 270X is a GCN 1.0 card and thus should be
> supported by experimental drm-next-4.8-wip-si branch.
> 
> Is it worth trying? AMDGPU is using a yet another PM system (PowerPlay) , so
> perhaps it works better, without having to blacklist?

That tree is using the same code power management as radeon, just ported to
amdgpu.