Can I control the case fan based on core Temperature?

1st Official Post

    Hi, I'm using a RPI 4 B (4GB) with LibreELEC 9.1.501 and have a case with "build in" fan which connects via GPIO 3,3 V.

    The fan is apparently doing a good job:

    Without Fan:

    Idle = ~ 63 °C

    4K Video= ~ 77 °C

    With Fan:

    Idle = ~ 45 °C

    4K Video= ~ 48 °C

    The issue is that I can hear the fan in my living room when no video is playing even if it's very subtle.

    My Questions:

    1. Is there a way to control the fan so that it only activates when I am playing a video or above a certain temperature threshold (like > 65 °C)

    2. If not, would it be alright to not use the fan? Should I avoid Temperatures close to 80 °C? It seems pretty high.

    • Official Post

    Your current fan probably does not have a fan controller (Only two pins - red 3.3v and black ground) so it's either on or off.

    There are off market options, mainly Fan-Shim unfortunately I have no idea if it will work with LE - you'll need to see if anyone else can confirm or deny. They also do a serious full Heatsink, which should help. (Depends if you have any HATs/RTCs installed on the GPIO.)

    Personally, I would remove the case and somehow improve the airflow.

    I wouldn't worry too much about overheating as the RPi4 will reduce the core frequency at 80 degrees and then throttle back the CPU at 85 degrees,

    All you need is a transistor and you can control your fan either on/off to a set temperature or use PWM (Fan speed control)with same wiring but different script.....A simple 5v 4mm fan with 2 wires will do the job if you set it right...let me know if you need more info..