There are some instructions on the Pimoroni website about how to assemble the Fan SHIM, but it’s simple enough. Two bolts are inserted up through the PCB, and a nut is tightened down on them to act as a spacer to lift the fan slightly off the PCB. Then the fan is fitted with the wires facing the lower side of the Fan SHIM. Two nuts are then run down on top of the remaining bolt thread to clamp the fan in place. Noting the orientation of the wires the JST is connected to is quite fiddly, but in the end, we did this with a pair of tweezers as it’s such a small connector.
The Fan SHIM can now be fitted to Raspberry Pi 4; it uses a friction fit over the Raspberry Pi’s header pins to hold it in place, so requires no soldering. Powering on the Raspberry Pi and without making any changes or installing anything, the fan starts running straight away. It was good to note that it was very quiet, barely perceivable at all.
Of course, we might not want the fan to be on all the time, so setting it up to automatically turn on and off at certain temperatures, akin to a regular laptop computer fan, was our next step. The team at Pimoroni have written a small Python library for fan control, and again the instructions online give you an easy-to-follow guide to installing and configuring the settings using the terminal app in Raspbian.
In the library example to automate the fan, the user can change the thresholds of what temperature the fan turns on, turns off, and how often it checks the temperature. It’s also set up to use the on-board LED to give visual feedback, from green to red, to indicate the temperature of the computer. You can also, using the example given, use the button on the side of the Fan SHIM to manually override the automated settings and turn the fan on and off. If you find an automatic set of settings you like, they will persist, and the Raspberry Pi will start the service on subsequent boot ups.
We found the fan to be effective as well. We set a load of YouTube videos running in numerous browser tabs and set the fan to kick in at 50 degrees and to turn off at 40 degrees which it did perfectly, and it only had to run for a minute or so to bring the temperature down. It really is a quick and effective solution. One thing that is worth considering is that the tactile button on the side of the Fan SHIM protrudes the edge of the Raspberry Pi footprint. While this is accommodated for in Pimoroni cases for Raspberry Pi 4, we have an aluminium case from another vendor which doesn’t have space for the button (yet – we have our rotary tool primed and ready).
With the latest firmware, Raspberry Pi 4 doesn’t overheat unless it’s under heavy load, but if you’re doing some serious number crunching, the Fan SHIM is a good cooling option that doesn’t take up too much space.
Pimoroni £9.60 shop.pimoroni.com
A small, elegant solution to Raspberry Pi 4 cooling.