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    3 MB vs 6 MB - 2.4 Ghz vs. 1.86 Ghz - 25 watts vs. 17 watts

    Discussion in 'Lenovo' started by hexproject, Sep 19, 2008.

  1. hexproject

    hexproject Newbie

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    hexproject, Sep 19, 2008
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  2. Tinderbox (UK)

    Tinderbox (UK) BAKED BEAN KING

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    FASTER = X200 with 3 MB L2 cache @ 2.4 Ghz at 25 watts

    LONGER = X200s with 6 MB L2 cache @ 1.86 Ghz at 17 watts
     
    Tinderbox (UK), Sep 19, 2008
    #2
  3. John Ratsey

    John Ratsey Moderately inquisitive Super Moderator

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    The slower CPU will give longer battery life, at least under light usage, because the CPUs are selected to have lower leakage currents. However, the maximum speed will be only about 75% of the faster CPU. The clock speed (GHz) makes the big difference to performance. The effect of the bigger cache varies depending on what you are doing but isn't much.

    I've got the P8600 in my Dell E6400 and one core runs several degrees cooler than the other, which suggests a significant difference in the leakage currents between the two cores. I can use RMClock to undervolt the P8600 at maximum speed from 1.20V to 1.05V which reduces the maximum power and heat.

    There's a lot of luck when getting these CPUs since Intel's specifications include wide tolerance bands and most CPUs doesn't use the specified power.

    I wasn't impressed by the ULV U7600 in my Toshiba R500, which seemed to run at the upper end of the specified power range. I would probably shoot for the faster CPU and hope it is one that doesn't use too much power.

    John
     
    John Ratsey, Sep 19, 2008
    #3
  4. Supermans

    Supermans Notebook Consultant

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    How can you detect leakage in the cores? What program or device did you use?
     
    Supermans, Sep 19, 2008
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  5. mikec

    mikec Notebook Evangelist

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    I think though, in actual use, you'd get about the same battery life, maybe a tiny bit longer with the 17 watt.

    I've found over the years, watts really don't matter in my day to day use. Sure, if you are at idle a lot (not using the computer), the battery will last longer, but once you starting using it, the processor draws between those two will not make a big difference in battery life.

    But you will notice a faster processor, so I would go that route.
     
    mikec, Sep 19, 2008
    #5