Out of curiosity and lockdown boredom I decided to see how far a Raspberry Pi Zero could be pushed using Peltier or TEC cooling.
A Peltier is essentially a heat pump, the heat is transferred from one side of the plate to the other causing one side to cool and the other to heat however they are terribly inefficient so are not widely used.
More can be read on how Peltiers work on wikipedia here: https://en.wikipedia.org/wiki/Thermoelectric_cooling
You can buy the thermoelectric cooling kit I used on Amazon here
Out of the 5 Raspberry Pi Zeros I own only one would boot with the Arm freq set to 1.5Ghz I chose this board as it stood the best chance.
I affixed the board to the cold side of the Peltier plate and started at 1200Mhz increasing by 50Mhz at a time until I reached 1500Mhz where the Pi Zero became unstable once again, I then decided to go back by 50Mhz at a time until I found a stable clock speed.
Each change was fully tested using stress-ng with the number of threads set to 3 for 10 minutes.
The final Overclocking settings that proved stable are as follows:
During this entire test the Raspberry Pi Zero stayed below -10 Degress Celsius even with stress running!
As can be seen above the Pi Zero was running at 1.5Ghz and it was even stable enough to benchmark.
I decided to run UnixBench as usual as its what I had to hand and its the benchmark tool used to gather the benchmarks across all of my SBC’s
The Raspberry Pi Zero at the stock 1GHz Arm Freq produced a result of 70, with the rather extreme overclock it benchmarked at 117! Thats a 67% increase in performance!
Whist this is a near pointless activity it was fun to push a Raspberry Pi Zero to its limits and this is likely the cheapest way to get into extreme overclocking. The Pi and the Peltier cooler ran for just under 4 hours whilst I did this testing and wrote this post. Here is a final photo taken just before this was published showing the frost build up.
I will removed as much of the ice build up as possible then put this poor Pi Zero somewhere warm, it may live another day!