View Full Version : [all variants] [CPU] Speedstep/EIST not working if CPU multiplier manually set in the BIOS

June 6th, 2012, 09:48 AM
Hi Linuxers !

I currently face a problem with my new computer. I testes it on all versions of K/Ubuntu 12.04, 12.10 64 & 32bits and the new Fedora: it always behaves the same:
if I set a specific max CPU multiplier in the BIOS (in order to overclock), the frequency reduction technology (call it "Speedstep", "EIST" or whatever) does not works on Linux while it works on Windows. In "idle", my CPU should lower its frequency but it does not under Linux (it does when I set the multiplier to "auto" in the BIOS).

My CPU: Core i7 3770K

How do I check ?

** watch grep \"cpu MHz\" /proc/cpuinfo => displays 3500 MHz for idle and 3501 on load for each core. I've read somewhere that it's normal and 3501Mhz stands for "max". So be it. But the CPU does not seem to lower it frequency to 1600Mhz as it does on Windows...

** cpufreq-info gives, for each core:
hardware limits: 3.50 GHz - 3.50 GHz
available frequency steps: 3.50 GHz, 3.50 GHz
available cpufreq governors: conservative, ondemand, userspace, powersave, performance
current policy: frequency should be within 3.50 GHz and 3.50 GHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency is 3.50 GHz.
cpufreq stats: 3.50 GHz:0.61%, 3.50 GHz:99.39% (475)

Between two configurations, one working and the other not working, the only difference is my manual setting of the multiplier in the BIOS.

Anybody got an idea ?

June 7th, 2012, 06:35 PM
Hmmm. Maybe this will help point you in the right direction: https://wiki.archlinux.org/index.php/CPU_Frequency_Scaling

I think this might be a software configuration problem.