FlightAware Discussions

Rpi running very hot


My piaware SD 5 running on a Pi 4 is running really hot. I have a 3.5 inch waveshare display connected as well. It is constantly running over 75°C. Any ideas on how I can get the CPU temp down? With the screen I expected it to get warm but this is way too high. Does anyone know how to turn off the screen after some time? Maybe that would help.

The waveshare displays don’t have control over the backlight so turning that off isn’t an option unfortunately.

Pi 4s do run hot, a fan (or some serious heatsink) is almost required, I’m not sure what you’d be able to fit with the LCD though.

Placing an 8 or 12 cm fan that blows sideways over the RPi is more effective than one might think even when spinning slow and that can be pretty quiet.
But that obviously needs some creative arranging especially with a display.

I’m not sure can you underclock / undervolt the RPi4 with any success?
Honestly if it were still available the RPi3B+ would be sufficient for many purposes but it’s not really available well any more.

I will check around to see how to underclock the pi.

I have been thinking about a good thermal pad or sink to see if that would help. Yeah placing a fan there isn’t easy, unfortunately.

Most of mine run with the POE unit, that has a built in fan, and a heat sink.
Not really a solution in this case but may work for others.

This article may help for limiting clock speed

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Thanks @jonhawkes2030 I will give it a try and see how it goes.

Even placing a fan behind the board could help a lot i think but only a test would tell.

What kind of heatsink do you have?

I have both of my Pi4 with an Armor Case where almost the whole case is the heatsink.
Even if i decided to use the version with two fans, my devices are constantly running below 50°C

Using the fans at 5V speed brings it down another 5-10°C

That’s the one i am using:


And keep your devices updated. The first series had issues with the heat.

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I use those on all of my Pi4s.

you only need a very small amount of airflow across the board and that will give you quite a significant temperature drop.

Looking at the 3.5 inch waveshare display, it might be possible to run it in conjunction with the RasPi POE Fan HAT. The RasPi HAT has the advantage over most third party units in that it does not use any of the GPIO pins for power or to control its fan speed. It was the only fan I could find to use in conjunction with my GPS hat.

Also, I think that I read that the fan will still function if power is supplied normally rather than via POE.

The problem with mounting a wave share LCD is that the card seems to rely on the GPIO mount and the top of the Pi’s ethernet and USB ports for support. To use it double stacked would require rigging some stand-offs on the side opposite the GPIO to take the pressure of touch input.

Note that even with a fan, getting air in to the unit is important. I previously had my set up in a case with a closer gap between the GPS and POE HATs - the new open set up reduced processor temperatures by 5 degrees C. (It lives outside in a section of PVC pipe.)

I don’t have a heatsink currently but I am going to order one and see how much that helps.

A Raspberry 4 should never be used without.

I have the same GPS setup, actually several GPS hats that I use for NTP.

I even have an Ardusimple dual band, multi-constellation GNSS receiver, however, I haven’t connected the PPS line for use with NTP.


I bought a cooler for myself and the temperature dropped from 68º C to 44º C.

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Well I have 3 x Pi 4’s and don’t have heatsinks on any of mine but there again all 3 have official PoE HAT’s! :stuck_out_tongue_winking_eye:

Currently my Pi’s are all in the loft running;
Pi: 40°C (This is a spare Pi doing nothing other than sitting there kept updated)
Pi-Hole: 39°C (Handles @120,000 queries a day)
Pi-Air 48°C (running an AirNav FlightStick feeding FA, FR24 & RB

The PoE fans run intermittently only spinning up when needed and on Pi-Air for example are usually @30s off/5s on and although very quiet and can’t be heard I would have preferred a fanless solution so I tried some back-2-back tests;

The official RPi Foundation fan-cooled PoE HAT consistently ran @10-15°C cooler than the Uctronics Mini PoE fanless HAT.

The large heatsink from Pi-Hut was pretty much useless with the bare Pi benching at 58.2°C and after application of the 15x15x15mm CPU heatsink showing 58.4°C an increase of 0.2°C temperature over the non-heatsink Pi although I concede that could have been down to different processes running at the time but showing no benefit whatsoever.

My own experience from testing was definitely worthwhile and showed the best solution for me by far was the official PoE HAT with the added advantage of the Pi not having to be near a power outlet and so can be hung remotely on the end of a very long single ethernet cable if so desired which was ideal for getting Pi-Air up in the far end of the loft as close as possible to the antenna.

YMMV of course…

Kind regards,

I completely agree, it works really well.

A while ago I bought the small fan for the official raspberry Pi 4 case. It is not that expensive, comes with a small heatsink and you can easily set the temp it starts in raspi-config or the desktop config menu.

I thought that even if I might not use it with the cleverly designed clip-on frame in the case, it might still be a useful fan to put in a different case. Unfortunately, it is very noisy, irritatingly so. Maybe it is ok to prevent occasional overheating in a remote location, but I do not think it is a solution you would want in a living space , let alone on your desk…

Six month graph of CPU temp for an RPI4 in my attic. This uses an Airspy so gets pretty busy.

Note that Uputronics have updated their GPS hat to provide for better cooling, with or without a fan.


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I do think using a Pi 4 to run PiAware is a bit like using a racehorse to pull a coal cart.

I use a Zero for this, pre lockdown would spot between 1500 to 2000 aircraft daily. No heating issues at all.

Appreciate older Pi models not readily available, plus not really much cheaper than a Pi 4


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