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ubuntu undervoltage linux-ppc

 

  • sudo add-apt-repository ppa:linux-phc/ppa
  • sudo apt-get install build-essential linux-generic-phc linux-headers-generic-phc
  • reboot
  • Download PHC: http://www.linux-phc.org/forum/viewtopic.php?f=13&t=2
  • tar -xvzf phc-intel-0.3.2-9.tar.gz
  • cd phc-intel-0.3.2-9/
  • make prepare
  • make
  • sudo make install
  • sudo rmmod acpi_cpufreq
  • sudo modprobe phc-intel

Find out default voltage setting:

  • cat /sys/devices/system/cpu/cpu0/cpufreq/phc_default_vids
  • Example: 35 26 19

Find out current voltage settings:

  • cat /sys/devices/system/cpu/cpu0/cpufreq/phc_controls
  • Example: 11:35 8:26 6:19
  • This are values for 3 frequencies
  • The number before the colon is the frequency id, the number after the colon is the voltage id
  • The voltage can be calculated: mV = 700 + VID * 16
    • 35 = 1,260V
    • 26 = 1,116V
    • 19 = 1,004V

Set voltage:

  • As root:
    • echo "11:34 8:25 6:18" > /sys/devices/system/cpu/cpu0/cpufreq/phc_controls