The MagPi - February 2020

04

Overclock your config

We’re going to use the config.txt file to set

a new upper limit for the clock frequency. Open

another Terminal window and enter:

sudo nano /boot/config.txt

Scroll down to the section marked:

#uncomment to overclock the arm. 700 MHz is

the default.

#arm_freq=800

And change the settings to:

#uncomment to overclock the arm. 700 MHz is

the default.

over_voltage=2

arm_freq=1750

Save the file with CTRL+O (press RETURN) and use

CTRL+X to exit Nano. Restart your Raspberry Pi.

sudo reboot

When the system starts up again, watch vcgendcmd

again to see your new, faster clock speed in action:

watch -n 1 vcgencmd measure_clock arm

Browse a few webpages and you’ll see speeds

around 1750000000 (or 1.75GHz).

05

Understanding over_voltage

The over_voltage command adjusts the core

CPU/GPU voltage, and accepts figures between ‑ 16

and 8. The default value is 0.

More CPU speed demands higher voltage and if

Raspberry Pi doesn’t get enough volts, you will see

a small lightning bolt appearing in the top right of

the window (at this point, the CPU will be reduced

to the 700MHz default speed).

06

Crank it up

Let’s try taking things a little faster. We’re

going to take the over_voltage setting to 6 and set

the ARM CPU to 2.0GHz. Edit the config.txt file

with the following settings:

over_voltage=6

arm_freq=2000

This is as high as we’re going to take over_voltage.

Reboot the Raspberry Pi and you’ll be running at

2.0GHz. Run watch -n 1 vcgencmd measure_clock

arm again to see the new upper limit.

The watch vcgencmd

command is used to

keep an eye on the

current CPU speed

Top Tip

Overclocking problems

Most overclocking issues show up immediately with

a failure to boot. If this occurs, hold down the SHIFT

key during the next boot. This will temporarily disable

all overclocking, allowing you to boot successfully

and then edit your settings.

Alternatively, remove the microSD card from your

Raspberry Pi and insert it into another computer. You

will be able to access the config.txt file and adjust

the settings from there.

TUTORIAL

36 magpi.cc Overclock Raspberry Pi 4