Difference between revisions of "RPi Overclocking"
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Revision as of 21:46, 6 August 2012
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!
These settings are also documented in one of the example configuration files mentioned on the config page.
|arm_freq||frequency of ARM in MHz. Default 700.|
|gpu_freq||Sets core_freq, h264_freq, isp_freq, v3d_freq together.|
|core_freq||frequency of GPU processor core in MHz. It have an impact on ARM performance since it drives L2 cache. Default 250.|
|h264_freq||frequency of hardware video block in MHz. Default 250.|
|isp_freq||frequency of image sensor pipeline block in MHz. Default 250.|
|v3d_freq||frequency of 3D block in MHz. Default 250.|
|sdram_freq||frequency of SDRAM in MHz. Default 400.|
|over_voltage||ARM/GPU core voltage adjust. [-16,8] equates to [0.8V,1.4V] with 0.025V steps. Default 0 (1.2V) |
|over_voltage_sdram||Sets over_voltage_sdram_c, over_voltage_sdram_i, over_voltage_sdram_p together|
|over_voltage_sdram_c||SDRAM controller voltage adjust. [-16,8] equates to [0.8V,1.4V] with 0.025V steps. Default 0 (1.2V) |
|over_voltage_sdram_i||SDRAM I/O voltage adjust. [-16,8] equates to [0.8V,1.4V] with 0.025V steps. Default 0 (1.2V)|
|over_voltage_sdram_p||SDRAM phy voltage adjust. [-16,8] equates to [0.8V,1.4V] with 0.025V steps. Default 0 (1.2V)|
ARM, SDRAM and GPU each have their own PLLs and can have unrelated frequencies. 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.
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.
- 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.