At the time of writing, an 8GB Raspberry Pi 5 costs 95 euros. That's not particularly good, but we can't call it “prohibitive” if we consider certain activities. One of them is overclocking: many enthusiasts have decided to explore the virtues of the mini computer under extreme configurations with liquid nitrogen and direct PCB mods. SkatterBencher on YouTube did some tests recently, and reached a respectable 3.6 GHz.
If we look back, the Raspberry Pi 5 debuted in September-October 2023 with 4 and 8 GB RAM versions. In August, a cheaper 2 GB variant appeared, but the rest of the hardware remained unchanged. Its SoC is a Broadcom BCM2712 with four Cortex-A76 cores at 2.4 GHz, which logically makes it the fastest in the series... but with all that power on the table, some users want to go even faster, and that leads us to overclocking.
A couple of months ago, SkatterBencher on YouTube reached 3 GHz on the RPi 5 using air. Obviously, the process demanded several adjustments and the presence of an extra fan, but that's not bad for a conventional cooling strategy. Now, what would be the limit of the Raspberry Pi 5 applying something more exotic like liquid nitrogen...?
Raspberry Pi 5 + liquid nitrogen
The general design of the Raspberry Pi 5 prevents the installation of traditional “pots”, but SkatterBencher found an alternative compact and heavy enough to “sit” on the chip. The good news is that it didn't take long to reach 3.6 GHz, but the bad news is that every attempt to cross to 3.7 GHz ended in a hang. The Raspberry Pi 5 runs the latest version of Raspberry Pi OS, and also has the NUMA Patch that increases its performance. SkatterBencher also raised voltages on several rails, but the silicon refused to cooperate.
The real problem is that these SoCs should scale their performance with voltage and temperature control. The RPi5 finds a certain phase of instability below -90 degrees Celsius, but when trying to rule out any voltage detail, SkatterBencher sought a solution in the ElmorLabs AMPLE-X1 module, a small monster that can generate 45A between 0.6 and 5V, and its installation requires major surgery on the Raspberry Pi 5. Unfortunately, that didn't help either.
The last adjustment was to replace the integrated oscillator (54 MHz) with a variable and external version. SkatterBencher discovered that the upper limit is 56 MHz, but by reducing its frequency to 46 MHz, he could fake a 4 GHz clock. Why “fake”? Because the reference clock of the oscillator is lower: 4000 x 46 / 54 = 3407 MHz real.
In summary, overclocking a Raspberry Pi 5 with liquid nitrogen reaches 3.4 GHz in benchmarks, and 3.6 GHz as an absolute maximum. Jeff Geerling reached 3.4 with air, so it's evident that the silicon lottery plays a very important role here. Anyway, 1200 MHz above the base is a notable result.
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