The Raspberry Pi Foundation released an official Raspberry Pi 4 Desktop Kit. The kit comes with a new plastic case featuring holes for every port on the Pi 4, but nothing at all for ventilation. This project uses the official Raspberry Pi 4 case, though you can use any other case to accomplish this project as well.
Most Raspberry Pi models don't need fans or heatsinks for everyday use—but the Pi 4 is another story. The CPU idles around 60°C. Running heavy processes can heat the board so much it hurts to touch. Too much heat will cause the CPU to throttle, causing serious performance issues.
Jeff revealed some telling images by photographing the Pi 4 with a thermal imager. Most of the heat appears to come from the USB-C power circuitry. Since the heat has nowhere to leave inside the Pi 4 case, he decided to install a fan. Here's a quick breakdown of the project.
Connect the fan's red wire to GPIO pin 4 (5V) and the black wire to GPIO pin 6 (ground). The fan should receive power automatically when the Pi is booted.
If you'd like your fan to only run when needed (based on Pi temperature), check out our Raspberry Pi fan controller guide.
After installing the fan, you may want to initiate a stress test to see how it's impacting the Pi. Jeff's observation resulted in a lower temperature that kept the Pi 4 well under its throttling point by about 20°C. You can find more details on performing a stress test in his original post. Don't forget to check out our guide on how to measure the core temperature of your Raspberry Pi.