The Raspberry PI 4's CPU heats up quicker than the previous models so keeping it cool is more important than before. How does the ICE Tower Cooling fan and Heatsink perform at keeping the Rpi 4 cool?
The Raspberry PI4 heats up quicker than the previous models so keeping it cool is more important than before. How does the ICE fan and Heatsink perform at keeping the PI4 cool?
The Raspberry Pi computers manage their temperature by reducing the CPU speed once the CPU temperature reaches 85 deg C. This not only cools the CPU but also slows it down making the active tasks take longer to complete. For the PI3 and older models, once the CPU is slowed to half speed is stays at the reduced speed. For the PI3B+ the cpu returns to 1.4 Ghz when it is under 60 deg C from 1.2ghz when it is between 60 and 85 deg c. The lower limit can be changed in the file /boot/config.txt - temp_soft_limit.
For the RPi4 the cpu goes back to full speed once the temperature falls back under 80 deg c. As there is currently no lower limit the CPU will soon go above 80 deg C and slow down again.
The Raspberry RPi 3 was the first Raspberry Pi that could get hot enough to need cooling while doing intensive tasks but this was a minimal requirement. The Raspberry Pi 4 is more powerful and uses more electricity, as a result heats up quicker. So keeping the CPU well below 85 deg C is more important than before to keep the PI4 running at full speed.
One option is to install a heat sink or use a heat sink case but these either won't reduce the heat at all or by only a few degrees without additional air flow.
The ICE Tower Cooling Fan from https://www.seeedstudio.com aims to keep your Raspberry Pi 4 nice and cool even in warmer environments with a 5.5cm heatsink and fan mounted on the CPU to dissipate heat quicker.
To see the how well it performs I done a series of real world tests to heat things up. This involved converting 10677 frames from a Pi Camera timelapse to a MP4 video in normal conditions and then in an ambient temperature of over 40 deg C.
To get a base line of the Pi4 CPU temperature it was left idle. The temperature was measured using the CPU's internal temperature sensor which showed it was at around 54 deg c.
Test 1: No Fan
The first test was done with no fan at all. The PI4 quickly heated up to 85 deg c and slowed down balancing the temperature at around 83 to 85 deg C.
The image to video conversion took 57 minutes.
Test 2: Cooling with Small fan only
Next I repeated the same conversion but this time a small 5v fan was attached about 1 cm above the CPU. During the test the temperature of the CPU was kept around 52 deg C. As the cpu was not throttled down the task was completed in 38 minutes. This shows that during the first test the cpu speed was reduced due to the temperature.
Fitting The ICE Tower Cooling Fan
Next I fitted the ICE Tower Cooling Fan to the Raspberry Pi 4 to repeat the test.
The Fan comes with a frame and mounts to attach to the PI4's mounting holes and a thermal pad, plus 2 spares, that stick to the CPU and the base of the heatsink to improve the heat transfer from the CPU. The ICE Tower Cooling Fan runs from the 5v or 3v GPIO ports. It is 5.5cm high so it won't fit with any standard cases. Separate brackets are supplied for the Raspberry pi's 3 & 3B+, a clear instruction book and a screwdriver.
Once the Fan is fitted it can be connected to the 5v of 3.3v gpio pins and Gnd so it will be permanently on while there is power. There is enough space around the GPIO to connect other devices but you won't be able to use HAT boards without fitting a GPIO extender and having the HAT sit adjacent to the PI. The Display port is accessible and so is the Camera port but you would need to connect the Camera ribbon cable before fitting the fan or it may be a bit fiddly.
Test 3: Cooling with the Ice Tower Cooling Fan
Now the ICE fan is fitted, the test was repeated. The CPU temperature was kept around 48 deg C and completed in the same time as the 5v fan. This was only an improvement of 4 deg C but the cpu took longer to get to the average temperature than the 5v fan did.
This graph shows the the results of the three test and the idle temperature.
Lets turn up the Heat
To see how the fans perfom in more extreme enviroments the tests were repeated but this time the Pi4 was put in a foil lined box and the ambient temperature was increased to around 40 deg C using a heat bag to see if the fans can keep the CPU under 85 deg C. A temperature sensor was inserted into the box to check the ambient temperature. There was only an air hole where the cables entered the lid.
Test 1: 40 deg C ambient temperature with no fan
With no cooling the CPU got up to 85 deg C and beyond hitting 90 deg C briefly. The test was stopped after 10 minutes as it was clear the Pi 4 could not get it's CPU temperature lower than about 88 deg C. The processor had slowed down significantly and was processing 0.8 of a frames a second compared to 3 to 4 frames per second during earlier tests. If it was left to run it would have taken over 2 hours to complete the test compared to 38 minutes at full speed. I spared it the effort and let it cool down. Though 40 deg C + ambient temperature is probably a bit extreme, for hot environments and confined spaces the RPi 4 may have difficulty regulating it's temperature and needs additional cooling.
Test 2: 40 deg C ambient temperature with a 5v fan
Repeating the test with the 5v fan the CPU got above 80 deg C within 2 minutes maintaining an average of around 82 deg C. This caused the test to take an additional 5 minutes at 43 minutes due to slow down by the cpu.
The fan was mounted on a plastic holder made from molding plastic which has a melting point of 60 deg C. This was attached to the top of the USB port. After the test I found the plastic had melted to the USB port which highlights how the heat transfers through the Pi's components when it gets too hot and cpu cooling is important for the whole device not just the cpu.
Test 3: 40 deg C ambient temperature with the ICE Tower Cooling Fan
The test was repeated once again using the ICE Tower fan. The ambient temperature was 42 deg C as the test was started. The ICE fan done a much better job at keeping the CPU cool as the temperature gradually increased taking 10 minutes to get to 70 deg C. The 5v fan had got to 70 deg C in less then 30 seconds. The average temperature was 70 dec C across the test peaking at 76 deg C just before the conversion completed at 38 minutes. The final ambient temperature was 46 deg C.
So in high temperatures the ICE Fan had successfully kept the Raspberry Pi 4 cool enough to run at full speed and significantly out performed using just a 5v fan.
The graph shows how tests performed. The ICE fan allowed the CPU to gradually heat up across the whole test. The temperature continued to be collected after the test to show how quick the CPU would cool after the test while still in high ambient conditions of 46 deg C. This is shown by the decrease in temperture from 38 minutes.
Test 4: Longer test at high ambiant temperature
Though test 3 showed that the Ice fan could keep the CPU temperature under 80 deg C in high ambient conditions it did hit the peak as the test come to an end. So I was interested to see if the temperature would keep rising or level of at around 75 deg C.
For a final test the box was heated up again to over 40 deg C but this time the RPI 4 was running a CPU load script to keep it working at 100% for a longer period. Both the CPU and ambient temperature was measured for the duration of the test.
As with the previous test, it took the CPU about 10 minutes to get to 70 deg C. The CPU temperature stayed below 75 deg C for the duration of the test even though the ambient temperature rose to 47 deg C. As the ambient temperature decreased the Ice Fan lowered the CPU's temperature by the same amount. As you can see in the graph below the Ice Tower Cooling Fan can keep the CPU within operating temperatures for prolonged periods in high temperatures. It is clear that this would have been maintained for longer periods if left to run.
After 1 hr 42 Mins the lid of the box was opened but the CPU was still at full load. The graph shows the decrease in CPU temperature as the box returned to room temperature.
Using a the 7 Inch Touch Screen
My PI4 is often connected to the 7 inch Touch Screen so with the ICE Fan connected to the PI I mounted it to the screen. To do this you have to reverse the mountings on the fan to connect them through the pi into the mountings on the screen but it all fits fine. Though the Fan is big it fits perfectly behind the screen without touching the table or whatever surface the screen is on. So if you are using the Touch Screen for an intensive project display the the Ice Fan is a viable option.
At room temperature the ICE Tower Cooling Fan does not significantly decrease the CPU temperature compared to a basic 5v fan at only 4 degrees C. Both will keep the CPU cool enough for general room temperature use. If you are a casual user of a Raspberry Pi and don't do a lot of intensive tasks then the fan would be too big to be considered. If you are using your Pi for intensive tasks and your environment is quite warm or the Pi is going to be in a confined space with little airflow then the ICE Fan would be a good addition. As the tests have shown, it will have no trouble keeping the Pi cool enough to run at full speed.
The GPIO port is accessible but could be a limitation for some projects if a HAT is required though it still could be used with a GPIO extender. Access to the camera port is restricted but accessible. The Ice fan is very quiet as you can only really hear the slight hum of the fan. The 5V fan is much more audible in comparison.
The ICE Tower Cooling Fan is available from https://www.seeedstudio.com
Note: This is not a paid review, Seeed have supplied the Fan for review and express my own opinions.