15" rMBP 8GB vs 16GB RAM battery life difference

Discussion in 'MacBook Pro' started by hammm, Apr 23, 2013.

  1. hammm macrumors member

    Joined:
    Apr 23, 2013
    #1
    Hi guys

    I'm gonna buy a new 15" rMBP soon and I'm wondering whether doubling the RAM will have a perceptible difference in battery life.

    So far I couldn't find anyone or any website that does battery life comparison between 8GB and 16GB RAM, holding other things constant.

    Battery life is very important to me, maybe even more so than performance. So if doubling the RAM will shave off like an hour or so then it's a no-go.

    Anyone care to share any statistics/experience?

    Thanks :eek:
     
  2. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #2
    Additional RAM won't consume measurable battery power and may prevent page outs, which could consume more battery power. There are many factors that impact your battery life much more than the amount of RAM you have installed. See the BATTERY LIFE FROM A CHARGE section of the following link for details, including tips on how to maximize your battery life.

    The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.
     
  3. hammm thread starter macrumors member

    Joined:
    Apr 23, 2013
    #3
    Thanks for directing me to the FAQ, but I've read it before and it didn't mention anything about the impact of RAM/page outs, hence my question.

    Is there any threads that discuss RAM and page outs? I'd be interested in finding out more of these stuff.

    Thanks :)
     
  4. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #4
    Page outs will have less impact on battery life with a rMBP than with a MBP with a spinning HDD that would consume more power. If you're currently running your anticipated workload on another Mac, you can check to see if you're maxing out the RAM that you have. To determine if you can benefit from more RAM, launch Activity Monitor and click the System Memory tab at the bottom to check your page outs. Page outs are cumulative since your last restart, so the best way to check is to restart your computer and track page outs under your normal workload (the apps, browser pages and documents you normally would have open). If your page outs are significant (say 1GB or more) under normal use, you may benefit from more RAM. If your page outs are zero or very low during normal use, you probably won't see any performance improvement from adding RAM.

    Using Activity Monitor to read System Memory and determine how much RAM is being used
     
  5. hammm thread starter macrumors member

    Joined:
    Apr 23, 2013
    #5
    Thanks bro! [​IMG]
     
  6. dusk007 macrumors 68040

    dusk007

    Joined:
    Dec 5, 2009
    #6
    I once read a deailed test for DDR3L which also included different size modules.
    Generally 16GB consumes about as much more power as DDR3L saves over normal DDR3. Or about as much as an HDD needs. It is not going to dramatically change anything. Maybe 5% difference at best.
     
  7. Brian Y macrumors 68040

    Joined:
    Oct 21, 2012
    #7
    Not even that. You might get like 2 minutes less off a full charge? Nothing major at all.
     

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