Turning off the GPU/HDMI is only for power consumption and some more memory and not for heat. I use SSH so HDMI is not needed on my PiOne.
With the old Jessie Armbian Pi-hole works without any problem. And I also implemented a 1 CPU core and low DRAM clockspeed during the night (as a some Linux learning on the job).
For now I left the H3consumption program behind me.