CPU Heatsink 12x12x18 Anodized Aluminum

Increases cooling when overclocking your Teensy 4.x

DESCRIPTION

The Teensy 4.1 and Teensy 4.0 nominally operate at 600MHz which provides all the power most applications need but can be overclocked up to 1.008GHz with adequate cooling.  The heatsink can also be used to increase cooling capability when operated at the nominal 600MHz.

PACKAGE INCLUDES:

• Qty 1 – 12x12x18mm tall anodized black aluminum heatsink
• Qty 1 – Thermal tape

KEY FEATURES OF CPU HEATSINK 12X12X18MM:

• 12mm square base
• 18mm tall
• 6063-T5 aluminum
• Black anodized
• Includes thermal tape for mounting

Many users of the Teensy 4.x products will never operate them over the default 600MHz where the processor is running within its guaranteed specifications and has all the horsepower that most applications need.  Tantalizingly though, the IDE allows faster overclocked speeds to be selected for those who simply like to push the boundaries or really need the fastest possible computational speed.

Increasing the clock speed can significantly improve the performance for number crunching as shown in the CoreMark test down below.  When the system limitation is due to I/O limitations such as SPI bus speeds writing to a display, increasing the clock makes little or no improvement.

When operated at 912MHz or higher, additional cooling of the CPU is needed to ensure it stays in its happy place.  This is done by mounting a heatsink to the top of the CPU to help dissipate the additional heat.

The heatsink simply attaches to the CPU using the supplied double-sided thermal tape which bonds very securely.  Permanent thermal adhesive can also be used.  Cleaning the top of the CPU and base of heatsink with isopropyl alcohol will help ensure a good bond.

The attached heatsink increases the thermal mass and effective radiating surface area of the CPU allowing it to dissipate heat more efficiently even with no airflow.  With airflow, the heatsink can dissipate heat very rapidly.

To use the adhesive tape, remove the white liner that is on the side opposite the blue liner.  You may need fine tweezers or a sharp Exacto blade to get under the corner of the white liner.  Once the white liner is removed, you can use the blue tab as a handle to position the now exposed adhesive side of the thermal tape onto the base of the heatsink and press down firmly to securely fasten it.  Next remove the blue liner and position the heatsink squarely over the CPU and press down on the heatsink firmly and evenly to secure the adhesive.  Do not press too hard or apply pressure unevenly as it is possible fracture the solder balls under the CPU, especially if uneven pressure is applied to one corner of the CPU.

OUR EVALUATION RESULTS:

For testing the heatsink, we ran the CoreMark benchmark program modified slightly to put the benchmark test in a repeating loop while also reporting the internal CPU temperature using tempmonGetTemp(); at the conclusion of each loop.  Each test was run until the temperature stabilized.

The CoreMark program is designed to work the CPU to its maximum on a set of calculations to determine its processing speed and so it works well for a worse-case test.  The program can be found here:  https://github.com/PaulStoffregen/CoreMark

The following results were obtained at a 21°C ambient temperature in open air with a Teensy 4.1 mounted on our Prototyping System for Teensy 4.1.  The system has good ground and power planes and the Teensy 4.1 has no additional load on any of its pins so a best case environment for the CPU.

Adding the heatsink decreased the internal operating temperature by 7°C with no airflow and 17-22°C with airflow.

Light airflow was achieved by placing a modest 30CFM fan 21″ from the heatsink so only a very slight breeze could be felt at the heatsink.

Strong airflow was achieved by placing the same fan about 3″ from the heatsink.

If the Teensy 4.x is being operated at elevated ambient temperatures such as in a warm enclosure, those measurements would all be justified up by approximately the amount of increase in ambient temperature over 21°C.

The thermals of the Teensy 4.x can also be affected by the heatsinking mass on its pins.  Ground and power pins that connect to large power planes can help pull heat away from the module. As one example, under the same environmental conditions, a Teensy 4.1 with heatsink running at 600MHz and no air flow measured 3°C hotter sitting on antistatic foam on the bench versus when mounted in the Prototyping System for Teensy 4.1 baseboard with good power and ground planes.  Conversely if it is driving heavy loads on its pins, that will increase the thermal load on the microprocessor.

Downsides to Overclocking and Heatsinks

The main downside of this heatsink is that it is relatively tall at 18mm, so requires adequate clearance above the Teensy 4.x.  There are of course shorter heatsinks available, but with all other things being equal, bigger tends to be better when it comes to heatsinks.

Another consideration would be if the Teensy is being operated in an environment with a significant vibration or shock component.  In that case, the effect of adding a large extended mass to the top of the BGA microprocessor chip should be carefully considered and in most cases would not be recommended.

The final point of consideration is that overclocking the Teensy 4.1 will tend to shorten its lifespan.  This is due to operating at higher internal voltages and temperatures thus creating more wear and tear on the chip over time.  This is usually not a major consideration for casual hobby use, but should definitely be considered for long-term commercial applications especially if operating in a high ambient temperature environment to begin with.

For maximum life, the Teensy 4.1 can be slightly under-clocked at 528MHz.  This lowers the internal operating voltages and reduces the internal temperature even compared to operating at the nominal 600MHz.  Many applications will never notice the performance difference.

Notes:  

TECHNICAL SPECIFICATIONS