RPi Overclocking

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Overclocking configuration

WARNING: Setting any (of the below) parameters which could potentially over-volt your Raspberry Pi, will set a permanent bit within the SOC, voiding your warranty. So if you care about the warranty on your Raspberry Pi do NOT adjust any voltages!

Also at your own risk, you can try the display overscan settings from our wiki. These overscan-settings were posted on the forum, but are not confimed to work...

Overclocking options

These settings are also documented in one of the example configuration files mentioned on the config page.

Option Description Default
arm_freq frequency of ARM in MHz. 700
gpu_freq Sets core_freq, h264_freq, isp_freq, v3d_freq together. See below
core_freq frequency of GPU processor core in MHz. Note that it has an impact on ARM performance because it drives the L2 cache. 250.
h264_freq frequency of hardware video block in MHz. 250
isp_freq frequency of image sensor pipeline block in MHz. 250
v3d_freq frequency of 3D block in MHz. 250
sdram_freq frequency of SDRAM in MHz. 400
over_voltage ARM/GPU core voltage adjust. [-16,8] equates to [0.8V,1.4V] with 0.025V steps. [1] 0 (1.2V)
over_voltage_sdram Sets over_voltage_sdram_c, over_voltage_sdram_i, over_voltage_sdram_p together See below
over_voltage_sdram_c SDRAM controller voltage adjust. [-16,8] equates to [0.8V,1.4V] with 0.025V steps. 0 (1.2V)[1]
over_voltage_sdram_i SDRAM I/O voltage adjust. [-16,8] equates to [0.8V,1.4V] with 0.025V steps. 0 (1.2V)[1]
over_voltage_sdram_p SDRAM phy voltage adjust. [-16,8] equates to [0.8V,1.4V] with 0.025V steps. 0 (1.2V)[1]

Clocks relationship

ARM, SDRAM and GPU each have their own PLLs and can have unrelated frequencies[2]. The GPU core, h264, v3d and isp share a PLL, so need to have related frequencies. PLL will be set to:

pll_freq = core_freq * 2^n, for smallest n satisfying pll_freq > 600MHz.

GPU core, h264, v3d and isp should all be integer divisors of pll_freq. So core_freq=480 sets pll_freq=960. That would allow a v3d_freq/h264_freq/v3d_freq of 320 with an integer divider of 3.

Tested values

The following table shows some successfull attempts of overclocking. These settings may not work on every device and can shorten the life of the Broadcom SoC. Warranty will be voided if overvoltage is used.

arm_freq gpu_freq core_freq h264_freq isp_freq v3d_freq sdram_freq over_voltage over_voltage_sdram
750 255 450
900 250 500
900 275 500
900 450 450
930 350 500
1000 500 450 6
1000 500 500 6

References

  1. 1.0 1.1 1.2 1.3 What this means is that you can specify -16 and expect about 0.8V as the GPU/core voltage. This is 0.4V below the normal value of 1.2. If you specify 16, you'd get 0.4V ABOVE the normal value of 1.2V, or 1.6V. The fact that someone carefully specified "8" and "1.4V" as the upper limit in the examples leads me to think that it is likely to shorten the life of your raspberry pi significantly if you would specify values above "8". So: don't specify values above zero, but if you do, don't go above 8.
  2. http://www.raspberrypi.org/phpBB3/viewtopic.php?f=29&t=6201&start=125#p126308