Raspberry 3B+ Overclock

It’s known we’re not able to overclock our raspberries from the raspi-config tool since the 3B model. However, we have another option to set the Raspberry 3B+ overclock, modify some params on  the /boot/config.txt file. So, let’s do it!

We just have to edit the file with the following line on a terminal window,

sudo nano /boot/config.txt

and near the bottom of the file we’ll add the following lines:

gpu_freq=500

sdram_freq=550

arm_freq=1550

over_voltage=8

force_turbo=1

Explaining these lines

• gpu_freq sets core_freq, h264_freq, isp_freq, and v3d_freq together. On Pi 3/Pi Zero /Pi Zero W core_freq defaults to 400 and h264_freq, isp_freqand v3d_freqdefault to 300.
• core_freq is the frequency of the GPU processor core in MHz. In other words, It has an impact on CPU performance because it drives the L2 cache and memory bus. Default value is 400 for the Pi 3 and Pi Zero and Pi Zero W. Note that the L2 cache benefits only the Pi Zero/Pi Zero W and Pi 1, but there is a small benefit for SDRAM on the Pi 2/Pi 3.
•  h264_freq adjusts the frequency of the hardware video block in MHz. Individual override of the gpu_freq setting, isp_freq sets the frequency of the image sensor pipeline block in MHz. Individual override of the gpu_freq setting, and v3d_freq, frequency of the 3D block in MHz, and independent override of the gpu_freq setting.
• sdram_freq modifies the frequency of the SDRAM in MHz. The default value is 500 on the Pi3B+.
• over_voltage regulates the CPU/GPU core voltage. [-16,8] equates to [0.8V,1.4V] with 0.025V steps. In other words, specifying -16 will give 0.8V as the GPU/core voltage, and specifying 8 will give 1.4V. Values above 6 are only allowed when force_turbo is specified: this sets the warranty bit if over_voltage_* is also set.
• arm_freq sets the frequency of the ARM CPU in MHz. Default value is1400 for the Pi 3B+.
• force_turbo param forces turbo mode frequencies even when the ARM cores are not busy. Switch this on may set the warranty bit if over_voltage_* is also configured.

  You can get more info about those settings at Raspberry Pi Docs.

Making some tests

Changing those parameters, we’ve got our Raspberry 3B+ overclock ready! Above all that system changes, I’ve tried to do some memory and system benchmarks, to set an appropriated values and try avoid data loss. Pick the right settings.

Some great settings for Raspberry 3B+ overclock are these highlighted in yellow.

Tests have been run with the sysbench utility.

sysbench --test=memory --cpu-max-prime=20000 --num-threads=8 run

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

hdmi_force_hotplug=1
gpu_mem=256
gpu_freq=500
sdram_freq=550
arm_freq=1550
over_voltage=8

gpu_mem=256
gpu_freq=450
sdram_freq=550
arm_freq=1500
over_voltage=8

over_voltage=8
gpu_mem=256
initial_turbo=60
sdram_freq=650
arm_freq=1550
gpu_freq=550
sdram_freq=550

I’ve also overclocked the Raspberry Pi 4B model, please take a look at the post.