Boot - Raspberry Pi System Software Reference - page 34

Minimum SDRAM Frequency
When dynamic clocks are used, the sdram_freq_min allows the user to configure a
minimum clock rate in MHz.

sdram_freq_min Description

400 Default in MHz

Avoid PWM PLL
The avoid_pwm_pll configuration parameter allows the user to unlink the core_freq
from the rest of the GPU. A Pi configuration note states, “analog audio should still work,
but from a fractional divider, so lower quality.”

avoid_pwm_pll Description

0 Linked core_freq (default)

1 Unlinked core_freq

Voltage Settings
The configuration parameters in this subsection configure voltages for various parts of
the Raspberry Pi.

Current Limit Override
When supplied, the switched-mode power supply current limit protection is disabled.
This can be helpful with overclocking if you are encountering reboot failures.

current_limit_override Description

Unspecified Default (limit in effect)

0x5A000020 Disables SMPS current limit protection

Over Voltage
The ARM CPU and GPU core voltage can be adjusted through the over_voltage option.
Use the values shown in Table 2-4 .