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  • Posts: 6
  • Registered: ‎06-27-2008
  • Location: Germany
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[T61] Processor C states hidden by BIOS

2008-06-27, 21:27 PM


with the help of Intel's powertop tool I found out why my T61 runs with slower fan when on battery than on AC. The reason is that the BIOS hides the low power C states from the operating system.

The core duo has the C states C1 to C6 (with C6 comsuning the least power) of which only C1, C2 and C3 are exposed by the BIOS to the OS when on AC and C1, C2 and C6 when on battery.

I don't understand at all why Lenovo is doing this as all current operating systems are very well capable of caring for power savings for themselves.

In particular, I very much like to be able to use the C6 state also in AC mode. There is absoltely no need why my notebook should produce more heat and noise when idling on AC than on battery.


I tried all reasonable BIOS settings to no avail. C6 stays hidden when on AC.


I kindly ask Lenovo to also expose the C6 state to the operating system, regardless of the AC/battery mode or at least provide a configuration option for this.






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  • Posts: 276
  • Registered: ‎02-04-2008
  • Location: Canada
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Re: [T61] Processor C states hidden by BIOS

2008-07-09, 20:08 PM

I will bump this thread as the questions asked are worthy of a good explanation.


Are the differences in CPU power states intentional or are they set in this manner to satisfy some other power/hardware requirements?


Could any Lenovo engineer(s) lurking these forums shed some light on this?



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