Can you undervolt/underclock a 2.6GHz to be like 2.3GHz in rMBP? (To Save Battery)

Discussion in 'MacBook Pro' started by Starfyre, Oct 25, 2013.

  1. Starfyre, Oct 25, 2013
    Last edited: Oct 25, 2013

    Starfyre macrumors 68000

    Starfyre

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    Nov 7, 2010
    #1
    Is it possible to underclock the 2.6GHz processor to behave like a 2.3GHz or 2.4GHz for battery life savings? (say for when you need to travel or when you need to max out the battery life and coolness, and are OK with sacrificing some performance/clock speed... is this possible?)
     
  2. Wuiffi macrumors 6502a

    Wuiffi

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    Oct 6, 2011
    #2
    Can you undervolt/underclock a 2.6GHz to act like a 2.3GHz in Haswell rMBP?

    Don't know if you can underclock it but there is no need for what you want. With things like dynamic power gating and other energy saving stuff it doesn't matter if you have a 2.0 2.3 or 2.6Ghz. If sou only do light stuff neither of this chips will run at said frequency. And without load the peocessor only takes a few watt.


    Edit: take a llok here: Macbook Air 1.3Ghz i5 vs 1.8Ghz i7. No difference when you only do some light work.
    http://www.anandtech.com/show/7113/2013-macbook-air-core-i5-4250u-vs-core-i7-4650u/4
     
  3. Starfyre thread starter macrumors 68000

    Starfyre

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    #3
    I would think the 2.6 is better silicon. If there was a way to just make to operate like a 2.0GHz....
     
  4. stevemiller macrumors 65816

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    #4
    i think the point being made is that it already does this.
     
  5. Starfyre thread starter macrumors 68000

    Starfyre

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    #5
    Does it? Under load, there is almost an hour difference. If the processor was underclocked to say the lower clockspeed of the other processor, then it shouldn't have as big of an impact under heavy loads. We wouldn't be seeing a 2.0 getting 10+ hours of battery, 2.3 geting 8-9 hours, and 2.6 getting something potentially lower (one person states 5 hours or less).
     
  6. simon48 macrumors 65816

    simon48

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    #6
    It should. I don't think we have a big enough sample size know for sure yet.
     
  7. stevemiller macrumors 65816

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    Oct 27, 2008
    #7
    i see your point now, and i guess it makes sense: there could be situations where you are doing demanding work on the road, but you intentionally want the processor to throttle itself so it doesn't chew through battery as fast.

    as for if that is technically possible, i don't know.

    but consider this, if for example, your task is encoding some video using the 2.0 vs the 2.6, then yes, the 2.0 might last longer on battery, but its also completing the task slower, so you might end up accomplishing the same amount on both machines.

    disclaimer: i don't actually know if thats how it would balance out, but its something to consider in assessing the situation.
     
  8. Starfyre thread starter macrumors 68000

    Starfyre

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    Nov 7, 2010
    #8
    Yes, I would rather the task complete slower than to have it eat battery life like a shark. There was an application called "Coolbook" that appears to do just that, but it does not support any of the newer processors or OS. Would love to know if something like this exists for the latest version and newest processors.
     
  9. Wuiffi, Oct 29, 2013
    Last edited: Oct 29, 2013

    Wuiffi macrumors 6502a

    Wuiffi

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    Oct 6, 2011
    #9
    Can you undervolt/underclock a 2.6GHz to be like 2.3GHz in rMBP? (To Save Bat...

    Then why get a 2.6Ghz if the 2.0 seems perfect?
     
  10. covertash macrumors member

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    Dec 26, 2012
    #10
    Perhaps in case of a change of heart, the power is on tap and can be switched back to full throttle when absolutely needed (or when just plugged back in to the power brick).
     
  11. MacModMachine macrumors 68020

    MacModMachine

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    Canada
    #11
    no advantage to doing this, on older cpu's yes.

    now cpu's can change voltage and cpu speed on the fly.

    when its not being used its using little to no power.
     
  12. Starfyre thread starter macrumors 68000

    Starfyre

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    Nov 7, 2010
    #12
    As mentioned earlier:

    When Plugged in - Set it to 2.6Ghz.
    When need battery life - Undervolt/underclock to 2.0Ghz

    That way you can get 10+ hours on the 2.6Ghz, but can also use the power at the expense of battery life when you need it. Win Win.

    ----------

    If it were so great at changing voltage, then 2.3 and 2.6 should be getting roughly the same amount of battery life under load. Its not. On average, the 2.6 be faster on average, but at the expense of battery life. Now instead of having the 2.6 perform "the average" compared to the 2.3. I want to be able to undervolt/underclock so it performs "below average", which should be equivalent to what the 2.3 does or even the 2.0.
     
  13. koppie644 macrumors regular

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    Oct 4, 2011
    #13
    However, the faster processor finished the job in less time, which will compensate the one hour you lost in battery life


     
  14. Starfyre thread starter macrumors 68000

    Starfyre

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    #14
    Right, which is why I want to have the control slow down the processor and allow it to give me one hour in battery life at the expense of finishing the job in more time.
     
  15. clystron macrumors newbie

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    Aug 11, 2011
    #15
    The question is will the same job require more energy on a 2.6 than on a 2.0 model. Faster processor needs more power but less time, slower one is just the other way around. Its called "race to sleep" and under the right circumstances the faster cpu can be more energy efficient.

    If the power is not used for something you need to get done but only for some useless flash-ad in the corner of your browser than the slower cpu will usually win ;)
     

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