2026-08-30
The Pi that runs the DNS filter sits on a shelf next to the router, and its little case fan ran at full speed all day. The CPU was sitting around 48°C, so it did not need to.
The official case fan is controlled by a firmware overlay. Setting a higher trip temperature in config.txt was enough:
dtoverlay=gpio-fan,gpiopin=14,temp=65000
Now it spins up a few times a day during updates and is otherwise quiet. The closet is a lot more pleasant.