How far can you push the Raspberry Pi? Like every other thing with a CPU, someone was bound to find out. The answer? 3.6 GHz by using liquid nitrogen, at least according to one modder.
Pieter-Jan Plaisier of SkatterBencher.com has pulled off a few overclocking feats, including pushing an Intel Core i9 14900K CPU to a staggering 9 GHz using liquid helium, but this latest one is probably among the most interesting. The Raspberry Pi 5 comes with a clock speed of 2.4 GHz, and these boards are not usually seen as something a diehard modder would like to overclock a lot. The result? It was brought up to 3.6 GHz. It's not a huge increase like what he achieved with the i9, but it's still a 50% clock speed increase which, if it's stable, could result in a notable performance increase.
His journey began with the goal of reaching 5 GHz, a frequency typically reserved for high-end desktop processors. Then, the goal seems to have been knocked down to a much more conservative 4 GHz. Despite his best efforts, however, the Raspberry Pi 5 stubbornly refused to budge beyond 3.6 GHz. He tried a bunch of unconventional methods to get past this. One of these included enabling NUMA emulation, a technique that improves performance in benchmarks. This allowed him to reach 3.6 GHz at ambient temperatures, but any attempts to push further resulted in system crashes, and not even cooling it with liquid nitrogen allowed him to get past that.
Suspecting that the Pi's voltage regulation might be limiting its potential, Plaisier took the risky step of connecting an ElmorLabs AMPLE-X1 power card, granting him finer control over the power circuitry. Despite carefully increasing the voltage, the 3.6 GHz barrier remained insurmountable. Attention was also turned towards the board's 54 MHz crystal oscillator. Using heat, he replaced it with an ElmorLabs External Clock Board, allowing him to adjust the input clock frequency. While he couldn't increase the input clock beyond 56 MHz, he was able to lower it to 46 MHz, which, in theory, should have enabled a 4 GHz Arm frequency. However, despite the Broadcom tool reporting a 4 GHz frequency, the actual clock speed was lower due to the reduced reference clock. The effective frequency, according to Plaisier, was 3.407 GHz.
3.6 GHz is still a very respectable increase. Seeing how it was achieved without the liquid nitrogen part and with ambient temperatures, some of you might be closing this tab and looking up how to do it. Even if your Raspberry Pi allowed it (you'd need to have been very lucky in the silicon lottery), we advise against this unless you're very experienced or don't mind completely breaking your hardware. Overclocking, on paper, gives you advantages in performance, but while you might not be able to immediately see a dangerous increase in the heat the CPU puts out (at least in this experiment), that doesn't mean there won't be one during daily use. Putting a heatsink or a fan on it might not be the worst idea.
This level of overclocking could also give leeway to stability issues, as the CPU wasn't designed to run that fast, and the CPU could break as well, making your Raspberry Pi 5 a not-so-pretty paperweight. There's a reason why overclocking is not mainstream in PCs, and when we do see it, an operating overclock is not nearly as extreme as these experiments are. After all, these experiments are only meant to see how far a chip can be pushed given the capabilities of the silicon inside—you're not meant to run a system at these frequencies for daily usage. A "more normal" overclock for the Raspberry Pi seems to range from 2.8 GHz to 3 GHz, depending on what your device is capable of.
Source: Raspberry Pi Forums, The Register