Raspberry Pi 4 PoE HAT

I recently installed Home Assistant with ZHA and wanted to place the device in a little more cramped space. The PoE HAT enables me to do exactly that.

One problem. The fan is a little on the loud side. With managed OS in HA there is no way to edit the /boot/config.txt file while running.

  1. Mount the SD card (or what ever storage you use) on any computer
  2. Locate config.txt on the root of the storage
  3. Add the following
dtoverlay=rpi-poe

dtparam=poe_fan_temp0=10000,poe_fan_temp0_hyst=1000
dtparam=poe_fan_temp1=65000,poe_fan_temp1_hyst=5000
dtparam=poe_fan_temp2=70000,poe_fan_temp2_hyst=5000
dtparam=poe_fan_temp3=75000,poe_fan_temp3_hyst=5000

The temperatures are specified in millicelcius. So the stage 1 of the fan is starting at 65 C and so on. I tried with different settings and found out that this is the most quiet setting and have sufficient cooling. The CPU is set to throttle at 80 C, and with this config it will rearly go over 70 C. Not to mention that 90 % of the users never use any cooling at all.

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