I have a number of RPi 4 boards that I'm clustering together in a single case.

To consolidate power to a single wall outlet, I have them all connected together via a dedicated switch with PoE at each port. At 15w under load, the power over ethernet supplied is more than enough for each node.

The problem is, the PoE HAT I'm using requires use of all 40 GPIO header pins.

I'll have no pins left on any of the nodes to power other devices, namely the case fans.

Is there a dummy device out there (in the same form factor as the Pi) that could power 4 50mmx50mm fans?


2 Answers 2


You can use a PoE splitter like this and free up all your pins. And here is the instruction to make one yourself.


It turns out the PoE HAT doesn't use the GPIO header, so a 2×20 pass-through header can be used to expose the pins for other uses.

With that, the goal of powering all nodes via a single power source is achievable! A big thank you to all who commented/contributed to my finding a solution!

  • The PoE HAT (like most HATs) uses I²C interface on pins 27,28
    – Milliways
    Feb 2, 2020 at 22:45

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