power management - How to stop Ubuntu overriding BIOS underclock during boot - Ask Ubuntu

i have decided turn old xeon e3-1241 v3 nas. obvious reasons want use little power possible have gone bios , have lowered clock speed 800mhz. part fine, wall meter shows machine pulling ~60w in bios.

now when go boot machine, somehow ubuntu boot process overrides bios set multiplier , happily pulls ~140w wall duration of the boot.

as finishes boot process hits crontab @reboot /usr/sbin/cpufreq-set -u 0.8ghz sets bios defined settings. prevent swapping ondemand @ 60 second mark have removed /etc/init.d/ondemand. happily stays @ 800mhz , 45-60w of time except when booting. perfect.. almost.

i need force stay @ 800mhz while booting intend set lower vcore voltage save more power (and prolong cpu/vrm/motherboard lifespans) cannot life of me work out why overrides bios settings during boot. when tries boot low vcore voltage panics half of time trying run cpu @ full 3.5ghz duration of boot process. wall meter confirms reading of high current pull during boot , since machine has nothing other ssd , server graphics card installed, @ point can rule out other factors being cause (they under 10w total).

it enters full power state around 1 second before hits crontab/rc.local , set 800mhz. sadly due low vcore voltage completion of boot process bit hit or miss.

having done fair amount of experimentation have found ways of controlling clock work such echo 800000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq. adding them crontab/rc.local/init.d work above mentioned second still of issue.

edit /etc/default/grub favorite text editor. find line starts grub_cmdline_linux_default= , place kernel option intel_pstate=disable on preserving previous current options (quiet , splash common) , spaces in between them quotes on either end.

example:

grub_cmdline_linux_default="quiet splash intel_pstate=disable" 

now update grub sudo update-grub

note:the other thing comes mind reducing power consumption replace boot/system drive ssd. (note can make data recovery in case of failure extremely difficult if not impossible)