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    Undervolting on the T60

    Discussion in 'Lenovo' started by Unununium272, May 31, 2006.

  1. Unununium272

    Unununium272 Newbie

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    How much success has anyone had at this, and how much has it padded your battery life? Is it something I should play with when I get mine or is it not worth the trouble?

    Regards,

    -U.
     
    Unununium272, May 31, 2006
    #1
  2. santasballz

    santasballz Notebook Consultant

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    i thought it undervolts automatically when idling or not full usage?
     
    santasballz, May 31, 2006
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  3. Unununium272

    Unununium272 Newbie

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    To my understanding(granted, I cut my teeth on older tech), it underclocks. If it does undervolt, you can always undervolt more...


    Regards,

    -U.
     
    Unununium272, May 31, 2006
    #3
  4. Smith2688

    Smith2688 Notebook Evangelist

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    It underclocks, it does not undervolt.
     
    Smith2688, Jun 1, 2006
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  5. santasballz

    santasballz Notebook Consultant

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    alright. my bad.

    what's the difference anyway?
     
    santasballz, Jun 1, 2006
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  6. ikovac

    ikovac Cooler and faster... NBR Reviewer

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    Hi guys. There should be some info in my sig.

    Hope it helps,

    Ivan
     
    ikovac, Jun 1, 2006
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  7. slemFM

    slemFM Newbie

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    Hi,
    Did you manage to undervolt the T60?
    Did you use addidtional software, or did you do it in bios?
     
    slemFM, Mar 25, 2007
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  8. drwho9437

    drwho9437 Notebook Evangelist NBR Reviewer

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    you can think of your CPU as one big capacitor if you like Zc = 1/(j*2*pi*C*f)

    V^2/Z = Power so power is proportional to the switching freq of your CPU and the square of the switching voltage. However the transistors need to be significantly above the threshold voltage for Si at normal doping levels this ~= .7 , my CPU is about 1.18V or something powered which isn't actually that close, you need room for noise and such.

    So yeah, baring typos it underclocks to save power as it is directly proportional to freq, and undervolting is helpful too. My CPU underclocks by a factor of 2 on battery by default for a power saving of ~50%, but the factor of sqrt(2) for the undervolt to make the same contribution would mean a supply voltage around .85 that's just not enough to have any noise margin, so we are stuck with underclocking mostly.

    (This assumes the dynamic power loss >> than anything else, in regular CMOS this is still so (most of the time))
     
    drwho9437, Mar 25, 2007
    #8