Keeping Your Raspberry Pi Cool

Any PC motherboard is practically useless until you add some cooling and other accessories. This is because modern processors require cooling as they generate heat when operating. This is regardless of whether the processor is an x86, x64, an ARM based system such as the Raspberry Pi (RBPi), any other Linux or Android chipset, MIPs, or belonging to any other design.

The general explanation is the internal circuitry within the processor is microscopic and does not have the adequate surface area to dissipate the heat it generates while operating. Therefore, heat buildup within the IC can be detrimental, affecting its performance, unless the heat is removed. Designers usually build-in some safeguards against temperature rise to make the processor fail-safe. For instance, the PC has this feature as a part of the BIOS, and combined with the power management software at the OS level, keeps the CPU from being fried.

The RBPi single board computers run on an ARM chipset that follows the Reduced Instruction Set Computing or RISC architecture. Unlike the x86/x64 chipsets that follow the Complex Instruction Set Computing or CISC architecture, ARM chipsets do not need BIOS, but instead rely on a text file to feed it BIOS-like instructions when booting up. Notwithstanding the differences, the RBPis are as much a computer as those based on the Intel or Apple chipsets are, and prone to much the same issues of heat generation.

A research team at Microsoft, working on AI models and methods of shrinking image recognition to run on RBPi SBCs, has found a simple but effective way to reduce the heat the RBPi CPU generates while running their processor intensive workloads.

An internal protection on the RBPi3 disables it from overclocking when the ARM CPU reaches a core temperature of 85 degrees Celsius. In severe cases of overheating, the internal protection may also shut down the CPU. However, such interruptions are a real problem for any complex machine learning model programs the tiny device is running.

It is usual for a user to place a small heat sink on the RBPi3 CPU to help it to dissipate the heat and keep it cool. However, as the team at Microsoft discovered, this cooling is not adequate for some intensive workloads. According to the principal researcher Ofer Dekel at Microsoft, the cooling kits offered for the RBPi include heatsinks for the CPU and other components, but this is not adequate. Infrared images of the board point out that more work is necessary in cooling the processor.

Adafruit already supplies a miniature fan running on 5 VDC that users can mount on top of the RBPi CPU. However, for those mounting the RBPi on a 7-inch touchscreen display, this tiny fan can be a hindrance.

Therefore, the Microsoft team designed and 3-D printed a different fan mount. The design allows them to mount the Adafruit cooling fan directly on to standoffs available on the 7-inch display. With this arrangement, although the fan is pointing directly at the CPU, it is positioned at an angle beside the CUP rather than sitting directly on top.