My Raspberry Pi 3B Plus is running Raspberry Pi OS (32-bit) Lite. I only made update, upgrade and install Apache2.

It is connected to my home network with 1Gb Ethernet cable (no WiFi). Network traffic to the RPi is virtually 0 Mbps.

There is no heatsink installed.

My htop is the following:


Which looks like it's almost free of any task.

However it is pretty hot. I can barely hold my finger on SoC and network chips. My thermal imager shows this:

thermal img1

thermal img2

(Note that the dark squares on the top image are reflective surfaces - which always looks dark on thermal images)

Highest temperature is 51°C with ambient 28°C.

I dont't have anything to measure current consumption, but I'd say that it is far more than normal. I remember that in idle my RPi 3B Plus was just warm a little bit.

  • What can I do to debug this situation?
  • What can I do to decrease power consumption?
  • What else besides SoC can contribute to the power consumption?

3 Answers 3


51 deg C is actually reasonably cool for a Pi3. My Pi4 regularly runs at over 60 deg C. Don't worry about it.

  • Can i decrease cpu frequency or anything else to make it cooler? Commented Jul 6, 2020 at 15:25
  • Why do you want it to run cooler?
    – CoderMike
    Commented Jul 6, 2020 at 15:26
  • It runs into PLA 3d printed case and if it run more cpu demanding task or will be laced into warmer environment it can damage the case. Commented Jul 6, 2020 at 15:28
  • 1
    I would suggest a 3d printed case that can be affected by heat is not appropriate for a Pi.
    – CoderMike
    Commented Jul 6, 2020 at 15:29
  • Besides, if this amount of energy is not necessary, why spend extra energy? Commented Jul 6, 2020 at 15:31

Like others said, 50°C is reasonable. I would not worry too much.

However, there are some things that you can do to decrease power consumption/temperature:

  • disable some services which you don't need to lessen the load (e.g. I disabled bluetooth & wifi because I only use ethernet cable)
  • underclock with arm_freq in config.txt - maybe underclock your GPU as well?
  • install a small (or big) heatsink
  • update firmware as addition to updating your kernel (check rpi-update which does both)
  • disable LED lights
  • Disable HDMI if you don't need it
  • blow at your RPI to decrease the temperature by a few degrees temporarily

Note: You can monitor the CPU temperatures with vcgencmd measure_temp. Makes all the blowing at your RPI more fun.

  • Additionally I was able to turn off HDMI which lowered the temperature by 3 degrees or so. By far it was the only thing I was able to spot any difference. What else did I try: lowered cpu freq to 400MHz, turned off WiFi and Bluetooth. Commented Jul 8, 2020 at 13:51
  • 1
    Right, I forgot about HDMI - I never close it since I use it a lot. Interesting, 3 degrees is quite a lot, it would be nice to see some tests if turning it off helps performance as well.
    – GChuf
    Commented Jul 8, 2020 at 14:00

My 3b+ feels a lot warmer than my plain old 3b: they are both idling most of the time. In fact they spend over 95% of their life idling. They are both housed in metal FLIRC cases. My point is, I don't want to pay for a heater: it's a waste of electricity. I just want a cool, efficient Raspberry Pi that I can leave on all the time and use as a git server for my home network. The other Pi is a DHCP and DNS server, so again is not taxed much at all. What makes the 3b+ run so much warmer than the 3b when idling?

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