Not Enough Juice? Squeeze Your Raspberry Pi By Overclocking
If there’s any hardware released in 2012 that you’re likely to fall in love with, it’s the sweet-as-sugar Raspberry Pi, a mini computer designed and built in the UK that has shipped all around the world. Equipped with an ARM processor and capable of running various operating systems (although the best results are with a particularly useful build of Debian installed) the Raspberry Pi is small enough to fit into a cigarette box and powerful enough to run a home server, media centre and much more.
However, some of these uses might benefit from some extra power – Raspberry Pi “juice”, you might say…
The Raspberry Pi’s Hardware
The Raspberry Pi comes equipped with the bare minimum required to make a useable computer – how else do you think they can make it so small?!
Along with the 256 MB of RAM, the computer wields a 700 MHz ARM11 processor. This might seem lowly compared with devices build with AMD and Intel chipsets, but the beauty of the Raspberry Pi is in its flexibility rather than its power. It is this flexibility that enables easy overclocking. Note that subsequent versions have increased RAM and additional ports and connectivity options.
What You Need to Do To Overclock Your Raspberry Pi
In order to overclock your whizz-bang micro PC, you will first need to have installed the Raspbian operating system (derived from the popular Debian OS). Our previous guide will help you to do this.
If you have had your Pi for a while and have been using Raspbian during this time (or downloaded the version linked to in our previous guide) then you will need to upgrade Raspi-config in order to add new functions to the configuration program. Do this in the command line, entering:
sudo apt-get update && sudo apt-get install raspberrypi* raspi-config
This essentially upgrades the device firmware. Once you’re done, reboot your Pi and run Raspi-config. This program will enable you to set various options , one of which enables overclocking.
To overclock, select the appropriate option in the Raspi-config menu and then make your choice from the displayed clock speeds, as illustrated.
Note that it is also possible to overclock your Raspberry Pi by creating a config.txt file. This is advised if for whatever reason you don’t wish to upgrade the Raspbian OS. Use Notepad++ to alter the config file on your Windows computer, available from here.
Once installed and loaded, open Settings > Preferences > New Document/Default Directory and select the UNIX radio button. Click Close and then CTRL+N to start a new file. In the file, add the following:
carm_freq=800 gpu_freq=300 sdram_freq=450
This set of instructions will increase the CPU to 800 MHz. All you need to do is alter carm_freq= in order to overclock the processor! Now all you need to do is save the file as config.txt and save this to the boot partition on the SD card of your Raspberry Pi (the 60 MB partition that is accessible from Windows).
Help, My Raspberry Pi Won’t Boot!
Unfortunately if you set the clock too high, your minicomputer will fail to boot. Don’t worry, however, as this can be overcome by resetting the overclock.
To do this, when you boot your Raspberry Pi, hold SHIFT on your keyboard. You should then run Raspi-config once again to set a lower boot.
If you have used the config.txt method and your computer won’t boot, edit the file to set a lower clock speed.
The Raspberry Pi’s official website suggests that running Quake 3 might be a good test to find out if your chosen clock speed is suitable and stable. Note that if your chosen Raspberry Pi case isn’t sufficiently vented, however, you may need to make adjustments for airflow. Some online vendors have started selling heatsinks for the Raspberry Pi processor – recommended if you want to run at clock speeds above 900 MHz.
A Juicy Raspberry Pi!
There are a couple of things you will need to take into account. Not all Raspberry Pis are built the same, so while you might hear of one person running theirs at a particular clock speed, this doesn’t mean that your device will be able to match this.
Similarly, your Raspberry Pi should be provided with a solid power supply, best achieved by using a good power adaptor with a good quality cable and micro USB connector. Ramping up the clock speed on your Raspberry Pi can improve performance on standard tasks such as browsing the web and document management, even gaming, but be aware that it might not have a great effect on a device used as a media center.
For the best results, step up the clock speed slowly, testing after each change – and enjoy tweaking your Raspberry Pi mini PC!