Introduction
In recent times there has been much discussion on whether or not to mount the heat sinks on the latest version of Raspberry, the Pi 3. Having a higher performance processor, this board should produce more heat. But this heat is still acceptable, or you need to buy a heatsink? Or maybe you should replace it with a fan? Or use them both? Let’s find out in this article the “rumors” about this much discussed topic.
Overheating the BCM2837 processor
On the net you will find many photos that show thermal thermal distribution of a Raspberry board when the processor is under stress. These photographs show that some points of the processor can reach 87 ° C. In other items instead of the temperature never exceeds 60 ° C. The difference between these measured temperatures could certainly depend on the type of operations and the type of stress to which it is subjected the processor. As some people say, in these cases the processor really is not working at full speed.
The processor in question is the BCM2837, which is mounted on Raspberry Pi 3. The technical specifications report that the operating limit temperature is 85 ° C. Indeed, the CPU should present various problems have already over 80 ° C. So if there are cases where the processor remains active for long periods at 87 ° C the situation could be dramatic for the life of Raspberry board and then it would be necessary to mount a cooling system with heat sinks and fans.
One of the witnesses to these high temperatures is Gareth Halfacree which published its thermal picture on the internet. These photos testify to the high temperatures reached by the processor.
In contrast, many other sites show much lower temperatures (around 65 °) well below the critical value. Well anyway their analysis does not look so accurate. In fact, thanks to software that keep under control the speed of the CPU, it was discovered the cause of the contrast.
From further tests it would appear that the low temperature is due to the fact that the port protection system the processor to work at 600MHz (instead of the default 1200MHz!). Then the system begins to produce less heat (see here). So that explains the low temperatures. If the configuration is changed, or is carried out an overclock, adding a cooling system with heat sink and fan is required.
In fact, the addition of only the heatsink is practically useless if not accompanied by a fan which allows the air to reflux. Indeed, it was experienced that this solution if applied to the Raspberry Pi 3 (the Raspberry Pi 2 never exceeds 65 ° C), it does maintain the speed of the CPU to 1200MHz and the temperature around 60 ° C even after several minutes of 100% CPU activity. So you will not see lowering of performance (see here).
Monitoring the CPU temperature and speed
Given the subject matter, it will be very useful experience firsthand all this. For example you may be of interest to have a script that monitor the temperature and the speed of the CPU during the working operations. I found on the net this interesting script.Write the following script and save it as checkCPU.sh.
#!/bin/bash
CPU=$(</sys/class/thermal/thermal_zone0/temp)
while [ $CPU -gt 30000 ]; do
CPU=$(</sys/class/thermal/thermal_zone0/temp)
MHZ=$(</sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq)
echo "$(date)"
echo "CPU: $((CPU/1000))'C"
echo "GPU: $(/opt/vc/bin/vcgencmd measure_temp)"
echo "MHZ: $((MHZ/1000))"
sleep 10
donechange the permissions
$ chmod ugo+x checkCPU.sh
and then executeit
$ sudo ./checkCPU.sh
The script will show the situation of temperature and speed every 10 seconds.
Installing heatsinks
There are several heatsinks on the market and their price is really ridiculous. Among which some Aukru alluminium heatsinks that cost practically 4 euros and adaptable also to Raspberry Pi 2
The basis of these heatsinks is practically adhesive with a thermally conductive plastic layer. You’ll need to paste it directly over the processors present on Raspberry Pi 3 chips.
Ecco come devono essere incollati i dissipatori sulla scheda.
On the market there is another model, also distributed by Aukru, slightly higher quality, which costs about 5 euros, and it includes a copper plate too.
The copper plate is pasted on the underside of the board where the processor resides
Complete Starter Kit
There are complete kits incorporating both heatsinks, a fan and a transparent box built specifically to secure the fan. One of these is EEEKit Starter Kit
The Haiworld kit is cheaper than the last, and is around 10 euro.
Conclusions
At the end of it all, you can infer from the facts that if you have to work intensively with the processor and / or the board is enclosed within a box or small houses, you must certainly add a cooling system by adding a heatsink on the CPU and cooling fan.[:]