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I've recently updated to Ubuntu latest LTS. My computer suffers from bad cooling management, and I need to be able to disable turbo boost in order to use it comfortably.

I had a script that was doing just that by using msr-tools, disabling turbo boost on all cores with :

sudo wrmsr -pX 0x1a0 0x4000850089 (X being the number of the core)

Since the update this is what I get with this command:

wrmsr: pwrite: Operation not permitted

Any clue on how to fix this?

Regards

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1 Answer 1

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I couldn't get my script to work with the latest version of msr-tools (probably discontinued as the github remains untouched since 2013). Perhaps Ubuntu 16.04 changed the way it stores settings for its CPUs drivers, and msr-tools fails to generate the proper file tree.

The workaround I found is to (sudo) edit the file:

/sys/devices/system/cpu/intel_pstate/no_turbo

Simply type "1" for no turbo and save... No reboot needed.

You can easily check if it's working with

grep MHz /proc/cpuinfo

And see if any of the outputs goes above stock frequency

cpu MHz     : 2000.000
cpu MHz     : 2000.078
cpu MHz     : 2000.000
cpu MHz     : 1999.921
cpu MHz     : 1999.921
cpu MHz     : 1683.828
cpu MHz     : 1732.265
cpu MHz     : 2000.078

I hope someone will find this useful! Regards

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  • On Linux Mint 18.3, this solution works just for a session. When I reboot, /sys/devices/system/cpu/intel_pstate/no_turbo is set again to 0. Does anyone know how to make this change permanent? Jan 12, 2018 at 9:20
  • I no longer use this, I can't recall if my workaround was permanent.. But I guess you could always script it at boot time
    – Fluffy
    Jan 12, 2018 at 11:17
  • I also thought of doing this but I was hoping for a more elegant solution. Thanks for the tip anyway, Fluffy. Jan 12, 2018 at 19:18

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