When Raspberry Pi 4's system on chip (SoC) achieves a certain temperature, it lowers its operating speed to protect itself from harm. As a result, you don't get maximum performance from the single board computer.
Fan SHIM is an affordable accessory that effectively eliminates thermal throttling and boosts the performance of RPi 4.
It's quite easy to attach the fan SHIM to Raspberry pi: fan SHIM uses a friction-fit header, so it just slips onto your Pi's pins and it's ready to go, no soldering required!
The fan can be controlled in software, so you can adjust it to your needs, for example, toggle it on when the CPU reaches a certain temperature etc.
You can also program the LED as a visual indicator of the fan status.
The tactile switch can also be programmed, so you can use it to toggle the fan on or off, or to switch between temperature-triggered or manual mode.
The assembly is really simple and almost takes no time
With the help of Python library you can control the fan (on/off), RGB LED, and switch. You'll also find a number of examples that demonstrate each feature, as well as a script to install a daemon (a computer program that runs as a background process) that runs the fan in automatic mode, triggering it on or off when the CPU reaches a threshold temperature, with a manual override via the tactile switch.