(In reply to iuno from comment #64)
> (In reply to Alex Deucher from comment #63)
> > 
> > Are you forcing the power state to high?  The mclk shouldn't be affected by
> > the display clock.
> 
> No, setting the refresh rate to 144 results in high mclk, even when I set
> power_dpm_force_performance_level to low or pp_dpm_mclk to 0. Using 120 Hz,
> I could echo 0 or 1 to pp_dpm_mclk. I also got the power meter on now:
> 
> memory dpm state 0  (150 MHz):  77 watts
> memory dpm state 1 (1250 MHz): 112 watts
> 
> So there is a difference of 35 watts. Using Windows, I'm below the 80 Watts
> even with 144 Hz.

Yes, that is independent of the patch in attachment 131983 [details] [review].  The driver
disables dynamic mclk switching for refresh rates above 120 hz to avoid
flickering.