Comment # 143 on bug 66963 from Alex Deucher

(In reply to comment #142)
> -       r600_enable_sclk_control(rdev, true);
> +       r600_enable_sclk_control(rdev, false);
> Does indeed fix it.

Unfortunately, that disables dynamic engine scaling which on your particular
board pretty much disables dpm since the voltage and mclk are static :(