FlightAware Discussions

Keeping the RPi cool does make a difference

Both of my RPis are in the garage. It can get very hot in there. One RPi is usually 5 to 10% lower in the number of planes received than the other. They have both been ‘optimized’ to the max, but the difference persists. That is not an issue.

Last weekend, this lower performing RPi was showing an alarm on the FA page about the core temperature being high, something like 75 Celsius or so, if I recall correctly.

I installed a small standalone fan to cool it down, and its performance increased, surpassing the other RPI. Since I had another standalone fan, I used it to cool the other RPi as well. After doing that, it has taken the lead again.

I knew high temperatures could negatively impact the RPi, but I was still surprised by the change. Even with the cooling, the temperature of the low performing RPi is around 5 degrees higher than the other RPi. I wonder if it could be an indication this RPi is failing.

At 12 noon, with the cooling, the temperature of both RPis are under 50 Celsius. It’ll likely increase in the summer. Let’s see how this plays out.


all Raspberries have a throttling mechanism which reduces CPU speed if temp is getting high. I think, this will have an impact to the overall performance.

To see if throttling is active enter vcgencmd get_throttled from the command line.

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Thanks. Both RPis return “throttled=0x50000”. No idea what it means, so a Google search is in order. :wink:

Edit: Found this: 0x50000 means throttled has occurred since the last reboot.

So, looks like both are throttling, even with the cooling.

Look here.

vcgencmd measure_temp

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You can use this script (it’s not mine) to give a nice output to check for thottling:



Yep, it happend to me several summers. The Pi3B was throttling to 600MHz, one “5V/3A” no-name power supply dropped the voltage to something like 4.8V… A fan is really needed.

Now i am using a laptop with better (active if needed) cooling.

Hey @Dxista, I am also dealing with temperatures in a hot Pi and found the Argon Pi hat fans work really well so far. The thing I really like is the fan speed gets a user-set curve and turn off when it’s cool enough. The 40mm fan lets you sub a quality fan if you wish. And it’s cheap.

If you are interested: Argon40 Fan Hat for Raspberry Pi

I’ve got another data run going right now to collect a day’s worth of temperature data to check the current setup and will post a new curve In the next day or so.

I bought Smraza RPi 4b Case w/Fan & 4 Heatsinks (<$10 at Amazon). They keep the RPi’s quite cool (<50°C) even in 100° F ambient temps. The fan is almost silent.

Has anyone used this RPi case with passive cooling?

GBP 7.64 (approx. US $9.37) + Free Shipping

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I bought two for my kids to use.
They seem to work OK, however, I have not done any stress testing.

I have several of that design, also a couple that have two small fans within the same framework and they do a fine job for the money. I doubt the small fans would last a lifetime, but anything to move some air around and over the fins helps no matter what. Passive is fine, but it’s super cheap and easy to find a decent USB powered fan to stick on top as well if you don’t mind the Frankenstein look.

If you are specifically looking to run passive, then I would have to suggest the Kodi/Flirc case - they look great and do work a bit better in my experience - and I live in Phoenix where ambient temps get over 115f outside in the shade and well over 150f in an attic, so I’ve tested a bunch of cooling options.


I’m going to replace the fan on the PoE hat that’s driving my Pi4 up the top of the mast. It’s too loud, and even though it’s 30ft up in the air, I can hear it vibrating down through the mast and into the house when it runs at full speed so I have to have it throttled back. It’s hit nearly 60°C today and although it’s been the hottest day of the year so far, it’s going to get a lot warmer.

It’s a tiny little 25mm fan so I’ve asked a friend to 3D print a 25mm to 40mm adapter for me and I’ll fit one of these Noctua fans. Noctua stuff is good and very quiet, especially with their sound deadening mounts. This one has double the throughput at full speed and I expect it to be nicely quiet as the spec show it at nearly 4dB quieter than the original PoE hat fan.

The adapter should be done tomorrow and the fan will be here on Saturday. I’m quite looking forward to doing this at the weekend as although I don’t think it’s likely to get to the level of throttling, I’m keen for it to be done before the summer kicks in.


I am using it with the two fans, but these are currently disconnected. It works as expected, but my CPU load is not that high to bring it into trouble.

Have it now in my home office on the floor, operating as a feeder, hosting Grafana/Prometheus and a local VRS instance.
Temperature graph the last seven days where it’s getting warmer over time here.
the drop in between was a problem i created by messing up the collectd process.

The fans seem to be not too efficient. The temperature did not change that much after i disconnected it.
In several discussions people reported they are too close to the case and cannot transport the fresh air properly.

Alright, this is going to sound a bit silly, but I live in a very hot climate and cooling is a huge issue. That said, I setup both my rigs to where they sit right on top of a laptop cooler much like this:

I’ve had to change it out about every other year because the fans suck and they stop working, but I can toss the RTL-SDR triple filter up at the antenna above the roofline in ~115 degree summer temperature, run about 35ft of high quality RG6 down to my indoor setup sitting on top of a silly laptop cooler (with a passive Flirc case) and I never see core temps get over 45c. The Airspy (on one rig) and the rtl-sdr dongles (UAT and other rig) also sit on top of the cooler keeping them chilly as well. It helps to keep the dongles as well as the Pi/RockPi cool as can be.

Perhaps the fans create some excess EMI, but I feel more comfortable with cool running electronics outweigh any negative effects of the extra EMI.

I can beat this…
Buy a small fridge and put the RPi inside…
Sorry it’s funny friday :slight_smile:



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Yes, I’m using one on my setup.
I have installed it inside a discarded PC PSU case and use the fan from the former PSU to move away the heat from the RPi. Without the PSU fan running the temperature circles around 60C, with the PSU fan on it circles around 40C.
I’m running the 12V PSU fan at 5V so it’s quiet but moves enough air to keep the RPi cool enough.
There is no noticeable difference in reception with the fan on or off, so it seems that the fan itself doesn’t cause any significant EMI.

The exact same model I’m using, bought at Walmart as well.

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