https://bugzilla.kernel.org/show_bug.cgi?id=61941
--- Comment #14 from Shawn Starr shawn.starr@rogers.com --- Somehow, when the CPU shifts frequency this is causing voltage changes that are affecting the GPU's switching DPM power states.
I will be trying this week my old tests with EXA to see if this holds true but this time keep the cpufreq governor to performance mode only.
I could be grasping at straws but really, nothing would surprise me these days :)