https://bugzilla.kernel.org/show_bug.cgi?id=61941
--- Comment #9 from Ilya Tumaykin itumaykin@gmail.com --- Changing gfx_clock_gating also doesn't help. There's one more thing though that I've changed alongside dpm: I've enabled aspm=1 for kernel driver.
I will remove aspm=1 from modprobe.conf so the driver will choose itself whether it should be on or off. I'll report whether this helps or not.