Kingston HyperX 1600 RAM and Decrease in Battery Life?

Discussion in 'MacBook Pro' started by scmguru, Dec 23, 2011.

  1. scmguru macrumors member

    Nov 9, 2007
    Installed a pair of Kingston KHX1600C9S3P1K2/8G in my MBP i7 (Early 2011/). After the install, it seems like my battery life has decreased enough to be noticeable.

    Anyone else upgrade to 1600 DDR3 ram notice this?

  2. GermanyChris macrumors 601


    Jul 3, 2011
    I have them, and I didn't notice any difference
  3. thundersteele macrumors 68030

    Oct 19, 2011
    I remember some other thread where someone claimed that more RAM would decrease battery life. I'm not sure if this is true.

    I remember reading a study that compared 1.5v and 1.35v RAM from different vendors. In that study, there were also notable differences between RAM from different vendors.

    I'm not aware of differences between 1333 and 1600, but in general better performance will mean higher energy consumption (assuming the same technology).

    The amount of power consumed by your ram is less than 5% of the total energy consumption of your machine, both under load and idle. I can't imagine that there is a notable effect in everyday use.
  4. dusk007 macrumors 68040


    Dec 5, 2009
    Depends on the Machine. On a 15" MBP running with dedicated graphics under full load yes but on a MBA or 13 MBP it is a lot more than just 5% under load.

    Just check iStat or coconut battery what the machine consumes and compare it here with others (under a very specific workload) or swap back the old RAM and test the same workload in both configurations.

    Maybe you just keep open more apps and that is the actual cause of your decreasing battery life. vs 4GB default RAM it should be only something like 2-3 additional W under load and maybe a few hunderd mW idle. Takes away a few minutes but nothing really noticeable.
    1.35V vs 1.5 should be a bigger difference. But 4 vs 8GB also makes a differnce like 20% under load (just the memory) idle increases more I think but that is still really low in absolute values. And as mentioned different vendors with otherwise the same specifications often have very different power efficiency.
    I once just checked spec sheets and although they can never be really trusted even on them the amps for idle and load for different modules from the same vendor are very different.
    I guess it depends on what kind of dram chips they use (30nm, 40nm, 50nm) and maybe also if they are single sided or double sided.

    Test it and you should see if it is just your paranoia. If not, send them back and order some others with a 2011 MBP I'd recommend 1.25V RAM it is like cutting away the power consumption of an HDD and today it sometimes sells for nearly the same money.
    The speed difference between 1333 and 1600 is just about non existent. You cannot even measure it with benchmarks most of the time.
  5. thundersteele macrumors 68030

    Oct 19, 2011
    You might be right.

    I think some time ago you mentioned a study called "An empirical study of performance and power scaling of low voltage DDR3."

    The test system has a total TDP of 45W... that seems to be much less than a MBP (the 15'' quad cores alone have a 45W TDP), probably closer to a system like the Air. The normal 8 GB RAM consumes up to 7.4 W under load, and around 700 mW when idle or lightly used. So it seems to be closer to 10% idle, and up to 15% under load on these low power systems.
    The power consumption of the RAM should not change much going to a MBP like system. So we are clearly above 5% even on the 15'' MBP, but most likely below 10% on all MBPs.

    Something that might be relevant to this thread is that in the study, they find a large difference in power consumption (about 20%) between different brands, while the difference between going from 4GB to 8GB seems smaller.
  6. GGJstudios macrumors Westmere


    May 16, 2008
    The difference between various quantities and specs of RAM will not make a noticeable difference in battery life. Your battery life is affected by many factors, all of which have greater impact than your RAM. Read the BATTERY LIFE FROM A CHARGE section of the following link for details. This should answer most, if not all, of your battery questions:
  7. mgartner0622 macrumors 65816


    Jun 6, 2010
    Colorado, USA
    Unless you've overclocked the RAM by allowing more voltage (which you can't do on a Mac so it's irrelevant) there is basically no way it should have more than a minuscule affect on battery life.

    OP, are you sure you just don't have more programs than normal open now that you have more RAM?
  8. scmguru thread starter macrumors member

    Nov 9, 2007
    Picked up a set of Samsung 30nm 4gb 1.35v ram this weekend.

    Im planning on testing if there is any difference in battery life over the next few days.

    I did test the samsung cl11 against the Kingston HyperX CL9 running at 1600. The samsung ram is a bit faster (approximately 5 percent per x bench ram test).. If battery life improves.. That would be nice.
  9. thundersteele macrumors 68030

    Oct 19, 2011
    That would be great, the results will be interesting. Although, for me it's too late already... I got my 8 GB with 1.5v

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