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Pi 5 overclock — stable 3.0 GHz

The Pi 5 ships at 2.4 GHz. With real active cooling (fan + heatsink, ideally a metal block), you can push it to 3.0 GHz with no throttle and ~25% faster decode on small LLMs running on CPU.

TL;DR

bash install/02_active_cooling_check.sh   # idle temp sanity check
bash install/01_overclock.sh              # patches config.txt with a backup
sudo reboot
bash bench/stress_test.sh                 # 60s stress + telemetry

If anything goes sideways: bash install/rollback_overclock.sh && sudo reboot.

What the patch does

In /boot/firmware/config.txt, the script appends a delimited block:

# --- OC block pi5-ai-server ---
arm_freq=3000
gpu_freq=1000
over_voltage_delta=60000
# --- /OC block pi5-ai-server ---
  • arm_freq=3000 — target CPU frequency (MHz)
  • gpu_freq=1000 — VideoCore VII at 1.0 GHz
  • over_voltage_delta=60000 — +60 mV on the SoC rail for 3 GHz stability

The original file is backed up to config.txt.bak.preoc on first run. The block is idempotent — re-running the script doesn't duplicate it.

Observed results (Pi 5 16GB + active alu block)

Load Frequency Load voltage Max temp Throttle
Idle 1500 MHz ~0.76 V 38°C 0x0
60s stress-ng matrixprod (4 cores) 3000 MHz ~1.00 V 62°C 0x0

Pi 5 thermal throttle kicks in at 80°C → 18°C of headroom. If your silicon is good you can try arm_freq=3100 + over_voltage_delta=70000, but test each step with bench/stress_test.sh.

Why the cooling check is mandatory

Without active cooling, the SoC will:

  1. Hit 80°C within seconds at 3 GHz
  2. Throttle down → worse performance than stock
  3. Long-term: shortens silicon lifetime

The 02_active_cooling_check.sh script reads the idle temp. If it's above 55°C, it bails — strong signal cooling is inadequate (or the Pi isn't actually idle when you ran it).

Recommended cooling

  • Official Raspberry Pi 5 active cooler (~$10) — what I use
  • Decent alternatives: Argon ONE V5, Pironman 5
  • Avoid for OC: passive heatsinks alone (even big ones)

Rollback

bash install/rollback_overclock.sh
sudo reboot

If the backup exists it restores the original; otherwise it strips the added block. You're back to stock 2.4 GHz.

Live diagnostics

vcgencmd measure_clock arm     # current freq in Hz
vcgencmd measure_temp          # SoC temperature
vcgencmd measure_volts core    # voltage
vcgencmd get_throttled         # 0x0 = perfect

get_throttled bits worth knowing:

Bit Meaning
0x1 currently under-volted
0x2 freq currently capped
0x4 throttle currently active
0x10000 under-volt has happened
0x40000 throttle has happened

0x50000 means "throttled in the past but fine now" — typically a brief spike during a stress test. Reboot then re-run the stress test.