Posts: 2
Joined: Mon Jan 29, 2024 8:59 pm

Pi400 overclock latest update?

Mon Jan 29, 2024 9:17 pm


New raspberry pi400 user, I’ve read all the guides online on how to overclock my pi.
I’m not sure if I’m missing something but when I use the /boot/config.txt route. The file opens and says moved to /boot/firmware/config.txt. This opens but the file does not match all the tutorials.

Am I missing something? How do I overclock my pi400 on latest software?

Thanks in advance

User avatar
Posts: 23330
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Pi400 overclock latest update?

Mon Jan 29, 2024 11:29 pm

The guides are out of date.

There were a lot of changes when Bookworm (the latest version of Raspberry Pi OS) was released. One of the major ones was that all files in /boot/ have been moved to /boot/firmware/

You should edit the files in /boot/firmware/

The rest of the guide is probably OK.

What differences do you see?
Unreadable squiggle

User avatar
Posts: 539
Joined: Wed Jan 27, 2021 5:22 am
Location: heaven

Re: Pi400 overclock latest update?

Tue Jan 30, 2024 12:27 am

Instead of /boot/config.txt edit /boot/firmware/config.txt
Raspberry PI 400 Raspberry Pi OS Bookworm Kernel: 6.6.17-v8+ DE: XFCE
Debian - "If you can't apt install something, it isn't useful or doesn't exist"

User avatar
Posts: 6247
Joined: Fri Jul 22, 2016 9:09 pm
Location: Eberbach, Germany

Re: Pi400 overclock latest update?

Tue Jan 30, 2024 8:32 am

Iuand wrote:
Mon Jan 29, 2024 9:17 pm
How do I overclock my pi400 on latest software?
I only added these two lines to my Pi400, now Pi5:

Code: Select all

pi@raspberrypi5:~ $ tail -2 /boot/firmware/config.txt 
pi@raspberrypi5:~ $ 
Of course for Pi400 you have to use 2100 or slightly above (default is 1800MHz).

Posts: 2
Joined: Wed Jan 31, 2024 10:32 am

Re: Pi400 overclock latest update?

Wed Jan 31, 2024 11:25 am

I recently re-overclocked my Pi400, using more modern methods and a bit of stress testing (taking into account the helpful info in HemannSW's posts). In terms of maximum overclock, the best I could achieve was with:


arm_boost=1 is already set in the Bookworm config.txt (and you definitely want it set).
over_voltage_delta=25000, is the equivalent of over_voltage=1 (i.e. an extra 0.025v).
Using over_voltage_delta is recommended instead of over_voltage these days, as over_voltage_delta still allows DVFS (Dynamic Voltage and Frequency Scaling) to work (over_voltage overrides it).

The best I could do without any extra voltage, was:


Both of these overclocks survived stress testing for over an hour, and didn't result in any throttling
$ sudo apt install -y stress-ng
$ stress-ng -c 4
$ vcgencmd get_throttled

I tried extra voltage, to see if I could overclock any higher (using various values for over_voltage_delta or the older over_voltage (with force_turbo=1 for over_voltage settings of >6)), but couldn't achieve a higher stable overclock.
I don't really want to risk killing my Pi400 with too much voltage anyway :roll:

Personally I use my Pi400 as a desktop PC.
I don't need it to stay at the maximum frequencies all the time (hence I don't use force_turbo=1).
I don't want the minimum frequencies to drop too low (to help with responsiveness), for which add the following into config.txt:


Posts: 360
Joined: Thu Feb 18, 2021 2:00 pm

Re: Pi400 overclock latest update?

Wed Jan 31, 2024 11:53 pm

Under Bullseye (haven't tried bookworm yet) my Pi 400 continues to be perfectly stable under all loads with just the following

Code: Select all

The firmware automatically selects a suitable voltage (for my Pi 400 that is).

Posts: 2
Joined: Mon Jan 29, 2024 8:59 pm

Re: Pi400 overclock latest update?

Sat Feb 03, 2024 4:06 pm

Sorry for vanishing!

It's me missing something. I'm completely new to all of this so have to admit, i'm struggling to understand most of the info! Please forgive my ignorance.

I've had another look today and this is the 'new' config file

GNU nano 7.2 /boot/firmware/config.txt
# For more options and information see
# http://rptl.io/configtxt
# Some settings may impact device functionality. See link above for details

# Uncomment some or all of these to enable the optional hardware interfaces

# Enable audio (loads snd_bcm2835)

# Additional overlays and parameters are documented
# /boot/firmware/overlays/README

# Automatically load overlays for detected cameras

# Automatically load overlays for detected DSI displays

# Automatically load initramfs files, if found

# Enable DRM VC4 V3D driver

# Don't have the firmware create an initial video= setting in cmdline.txt.
# Use the kernel's default instead.

# Disable compensation for displays with overscan

# Run as fast as firmware / board allows

# Enable host mode on the 2711 built-in XHCI USB controller.
# This line should be removed if the legacy DWC2 controller is required
# (e.g. for USB device mode) or if USB support is not required.


What i'm struggling to understand, is where in this file do i place this code?


does this (# Run as fast as firmware / board allows
arm_boost=1) have any relevance?

Posts: 9262
Joined: Tue Jun 30, 2015 1:35 pm

Re: Pi400 overclock latest update?

Sun Feb 04, 2024 3:48 pm

- simply put it under 'all'

Overclocking the GPU is silicon lottery! So better start without it and see how far you can push your Pi400.

Posts: 2
Joined: Wed Jan 31, 2024 10:32 am

Re: Pi400 overclock latest update?

Tue Feb 06, 2024 10:41 pm

After more testing, Undertow's settings from earlier in this thread, work better than my previous best (and don't need any extra voltage).
I would try those settings & drop the arm_freq, if it's not stable enough.

My previous fastest settings:


Undertow's better settings:


The gpu_freq of 870, is key to hitting that arm_freq of 2350 (I couldn't hit it, with a gpu_freq of 750 or 800).
Those settings are stable through a Geekbench stress test for me (which lasts about 20 minutes).
A 'stress-ng -c 4' stress test, creates enough temperature to start throttling after about 25 minutes. As I'm using my Pi400 as an internet browsing & office type desktop 'replacement', it will never be working that hard for that long, so it's not a problem for me ;)

You asked about arm_boost. This is what the documentation says about it: 'All Raspberry Pi 400s and newer revisions of the Raspberry Pi 4B are equipped with a second switch-mode power supply for the SoC voltage rail, and this allows the default turbo-mode clock to be increased from 1.5GHz to 1.8GHz. This change is enabled by default in Raspberry Pi OS. Set arm_boost=0 to disable.'
So it's already in your config.txt and sets your Pi 400 to run at a default of 1.8GHz, unless you are overclocking further ;)

Return to “Raspberry Pi 400”