Hardware Reference
In-Depth Information
These days, overclocking refers to changing any sort of setting to get performance
above and beyond the default configuration of the hardware. As an example, some
people have resorted to any number of tricks and hacks to get a performance boost,
including immersing the entire system in liquid nitrogen cooled Flourinert. Some peo-
ple are crazy.
This is an excellent time to warn you: trying to overclock your Raspberry Pi will
almost certainly make the hardware burn out quicker, possibly immediately. It will
also probably not double your performance, and if by some miracle it did, you
probably wouldn't be able to run anything reliably on the overclocked Raspberry
Pi.
Then again, this is a $35 PC. You live only once. (When you decide to really take
that advice to heart, try
Hack #40
.)
Remember that the heart of the Raspberry Pi is a Broadcom system-on-chip, with an
ARM CPU, a Videocore IV GPU, and 512 MB of RAM. Each of these parts have its own
clock frequencies, and the GPU has adjustable clock frequencies for its subcompo-
nents. Specifically, the GPU has a core frequency, an H264 frequency (the H264
hardware video decoder block), a 3D processor frequency, and an image sensor pro-
cessor frequency.
You can tweak all of these settings by changing options in
/boot/config.txt
. This file
may or may not exist; if it does not, just create a new empty file.
Increase ARM CPU Frequency
Let's start with the most obvious overclock: the ARM CPU. The frequency of the ARM
CPU (
arm_freq
) defaults to 700 MHz. To speed it to 900 MHz, add this line to
/boot/
config.txt
:
arm_freq=900
Then, when you reboot, the hardware will try its best to honor your request. But re-
member, this isn't magic. No matter how badly you want to put
30000000
as the fre-
quency, it isn't going to work. People with a lot of experience overclocking hardware
have determined that the Raspberry Pi does not usually successfully overclock be-
yond 900 MHz, unless you use
overvolting
(see
Hack #07
).
Increase SDRAM Frequency
Another simple way to overclock is to increase the frequency of the SDRAM memo-
ry. The frequency of the SDRAM memory (
sdram_freq
) defaults to 400 MHz. You can
usually increase this value to 500 Mhz without issue by adding this line to
/boot/
config.txt
:
