Whilst we await Software/Firmware updates from the Raspberry Pi team to reduce power usage and thus reduce temperatures, I’ve continued to investigate options for managing the Hot Raspberry Pi 4.
Since the release of the Raspberry Pi 4, we’ve seen a rise in 3rd party enclosures, some of which clearly aim to tackle the issue with heat management. I’m a proponent of silent, fanless, passive cooling solutions. I think that’s a big plus for previous Raspberry Pi generations, it would be a shame to lose this ability with the Raspberry Pi 4. Time to investigate and see if silence is still possible.
In a follow-up post, I have examined the impact on WiFi signal strength when the Raspberry Pi 4 is housed in different enclosures. Will metal cases or electrical noise from fans have an impact?
Update 4 September 2019: A further round of testing has been performed with various enclosures under load/stress. See this new post to look at both temperatures and CPU thermal throttling.
Whilst there are new cases appearing regularly, I don’t have the time and means to evaluate them all. So I’ve aimed for a fairly representative set of enclosures available (as of Aug 2019), many of which are generic and sold under various names:
Passively Cooled Enclosures
These passive enclosures provide varying degrees of protection and access to the key features of the Raspberry Pi 4.
The Armour radiator and Pibow Coupé cases leave a lot of the board exposed. The Pibow is a little bit more flexible as you can continue to use HATs, whereas the Armour is more restrictive, though with some header extensions you probably could still accommodate some HATs if needed.
The Generic Aluminium case, secures the board within a full metal frame, providing ventilation holes on top, and a slot on the side to feed out a ribbon cable that might connect to the GPIO header. It was supplied with a set of 4 vaned heatsinks of varying sizes and a copper(?) plate for on top of the wireless module (according to the instructions). These heatsinks were fitted during the testing with and without the fan installed. The metal case would benefit from a set of rubber feet, to keep the metal chassis off delicate surfaces. Unfortunately, you can’t use it with the Pimoroni Fan Shim to be installed, as the edge of the case presses against the button/switch on the Fan Shim
Actively Cooled Enclosures
I’ve touched previously on some active cooling options for the new Raspberry Pi 4, but there are now more options available.
The Armour twin fan radiator enclosure is very similar to the passive version, but with some of the fins removed to provide space to house two small (25mm) fans which connect to 5V on the GPIO header for power. Like the fanless version, most HATs won’t fit and other parts of the board are still exposed. Due to the fans being mounted flush against the metal of the enclosure, these fans will struggle to create any real airflow.
The generic aluminium case with its ventilation holes allows bolts to be used to secure the 30mm fan to the case. Like the Armour case, the fan is powered via the 5V supply on the GPIO header. The fan was tested with it sucking air in from the top and with it blowing it out.
The Fan Shim sits snugly within a space carved out of the Pibow Coupé 4 case. This 30mm fan is connected via the GPIO header and from this can be temperature controlled, so that it doesn’t run all the time unlike those just wired to the 5V power rail. However, as before using HATs are going to be a problem, perhaps more so given the shim is utilising more than just the header for power. Pimoroni explains this: “Because Fan SHIM uses pin BCM18 to control the fan, and this pin is also used by I2S audio devices, you won’t be able to use I2S DACs like pHAT DAC, pHAT BEAT, and the IQAudio boards at the same time as Fan SHIM“. You can, of course, use the Fan Shim with other enclosures, but not all of them will fit.
The measurements are taken with the Pi idle at GUI Desktop, both WiFi and ethernet are connected, though mostly idle. The Pi is fully updated with public updates as of 18 Aug 2019 (Raspbian Kernel version: 4.19.58-v7l+). Temperature measurements are taken using:
- CPU Temperature –
/opt/vc/bin/vcgencmd measure_tempand RPI Monitor
- Case Temperature – Infra-red thermometer
- Ambient Temperature – 433Mhz wireless room temperature and humidity sensor, connected to my HomeAssisstant.
Results: Passively Cooled Enclosures
|RPi4 Bare board (non-enclosed reference)||22||61||39||49||27|
|RPi4 Official case||24||73||49||43||19|
|Armour aluminium radiator||24||45||21||45||21|
|FLIRC Raspberry Pi 4||23||55||32||42||19|
|Generic aluminium (with heatsinks)||19||59||40||35||16|
|Pimoroni Pibow Coupé 4||23||65||42||40||17|
In terms of temperature management, the Official Raspberry Pi 4 enclosure stands out from the crowd, but only in a bad way, with the CPU temperature getting close to thermal throttle limits.
The FLIRC case which combines an aluminium chassis which interfaces with the CPU (via a small thermal pad) to transfer the heat to the metal part of the case. The base is made of plastic and the metal top part of the case is also covered in black plastic. However it’s constructed, it shows some clear benefits over the other solutions. Keep in mind, these tests are with the Raspberry Pi 4 sitting idle.
The Armour/Radiator design provides the best cooling, with the enclosure reaching temperature equilibrium with the CPU, and keeping the CPU at just 21°C above ambient.
Results: Actively Cooled Enclosures
|RPi4 Bare board (non-enclosed reference)||22||61||39||49||27|
|Armour twin fan aluminium radiator||25||42||17||32||7|
|Generic aluminium (with heatsinks) fan blowing out||21||38||17||25||4|
|Generic aluminium (with heatsinks) fan blowing in||21||38||17||25||4|
|Pimoroni Pibow Coupé 4 with Fan Shim (always on)||24||41||17||28||4|
With any form of active cooling, the Raspberry Pi 4 runs at just 17 °C above ambient. To test the real capabilities of active cooling solutions we’d need to look at stress/load testing the Raspberry Pi. Sitting at idle the fans can help dissipate the heat easily.
- The 30mm fan supplied with the Generic aluminium case was very loud, worse, well higher pitched when blowing inwards. But neither configured was really tolerable. A different fan, or running at a lower voltage might resolve the issue.
- The Fan Shim was set to be always on and didn’t utilise the additional software available to provide temperature-controlled activation, this was purely for testing purposes. This is a feature of the fan should be taken advantage of, if you can accommodate the Fan Shim on your header.
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- Passively cooled enclosures:
- Actively cooled enclosures: