Raspberry Pi 4 Overclocked!

This Raspberry Pi 4 overclock guide documents how to safely push the Pi 4B beyond its stock 1.5 GHz clock. With a few lines added to /boot/config.txt and decent cooling, you can push it noticeably further — with benchmark results across multiple clock profiles to help you find a stable configuration.

I have also overclocked the Raspberry Pi 3B+. If you are on that model, check out that post for specific settings.

Before you start: cooling is non-negotiable

Overclocking increases power consumption and heat. Running the Pi 4B at higher frequencies without adequate cooling causes the CPU to throttle back — negating any gain, or worse, causing filesystem corruption on the SD card. At minimum, fit a quality heatsink on the SoC. An active cooling case or a fan will give you much more stable sustained performance.

Applying the Raspberry Pi 4 overclock

Open the boot configuration file:

sudo nano /boot/config.txt

Scroll to the bottom and add the following. These are a conservative starting point — the benchmarks below show how far you can safely push it:

over_voltage=6
arm_freq=1750
gpu_freq=600

Save, exit, and reboot. If the system boots stably you can push the values further.

What each setting does

arm_freq — The ARM CPU clock in MHz. Pi 4B default is 1500. This is the primary lever for CPU performance.

over_voltage — Core voltage adjustment. Range [-16, 8] maps to [0.8 V, 1.4 V] in 0.025 V steps. Higher frequencies need higher voltage to remain stable. Values above 6 require force_turbo=1 and will set the warranty bit.

gpu_freq — Sets the GPU core, H.264, ISP, and V3D clocks together. Default on Pi 4B is 500 MHz.

force_turbo — In any Raspberry Pi 4 overclock setup, this forces the CPU to hold the configured frequency regardless of load, bypassing the dynamic governor. Guarantees consistent performance but increases idle power and heat. Combined with over_voltage above 6, it permanently sets the warranty bit.

For the full reference, see the official Raspberry Pi documentation.

Benchmark results

Benchmarks were run with sysbench, computing primes up to 20,000 on all four threads:

sysbench --test=cpu --cpu-max-prime=20000 --num-threads=4 run

The highlighted row (arm_freq=1650) delivers the best balance of speed and stability. Note how jumping to 1700 MHz causes a dramatic spike in maximum per-request time, indicating thermal or voltage throttling.

[Default] arm_freq=1500

arm_freq=1600, over_voltage=8

[Recommended ★] arm_freq=1650, over_voltage=8, gpu_freq=600

[Avoid] arm_freq=1700, over_voltage=8

The 1700 MHz run shows outliers up to 33 seconds for a single event — a clear sign of throttling. Your results may vary; silicon quality differs between boards. Always run a prolonged stress test (stress-ng for 30+ minutes) before relying on an overclocked Pi in production.