CPU Speed vs. Battery

Discussion in 'MacBook Air' started by jason.siegel, Jun 15, 2011.

  1. jason.siegel macrumors 6502

    Joined:
    Jun 15, 2011
    #1
    I'm planning to buy a 13" Sandy Bridge Air, and am wondering about the tradeoff between CPU speed and battery life. What effect will a CPU upgrade have on both performance and battery life? i.e. Does a 10% bump in CPU speed correspond with a 10% increase in performance and a 10% decrease in battery life?

    I will be using the notebook in law school, primarily for note-taking, web browsing and movies. I rarely play games or edit video, although I occasionally edit photos.

    Thanks!
     
  2. Hellhammer Moderator

    Hellhammer

    Staff Member

    Joined:
    Dec 10, 2008
    Location:
    Finland
    #2
    Newer CPUs are much more efficient so even though they are faster, they also provide better battery life. C2D to Sandy Bridge won't bring huge battery life improvements but at least the battery life should not be decreased.
     
  3. The-Pro, Jun 15, 2011
    Last edited: Jun 15, 2011

    The-Pro macrumors 65816

    Joined:
    Dec 2, 2010
    Location:
    Germany
    #3
    i doubt the cpu change will increase battery life. Maybe when the cpu is like 95%+ idle you might be able to get a slightly better battery life. But as soon as you but the cpu under some load id expect the battery life to be less. For example my friends 2.66 C2D 15" MBP 2009 under full CPU usage had 15 minutes more battery life than my 2.66 i7 15" MBP 2010 which has a bigger battery (400mAh more). So under load the new chips seem to be using a fair amount more power then the C2D's :(
    I definitely realised though that my 15" MBP uses far more power as soon as the CPU is less then 90% idle. Like no kidding my battery life dropped to 3.5 hours when i was utilizing 12% of my CPU. my friends when using 15% was around 4.5 hours. :(
     
  4. jason.siegel thread starter macrumors 6502

    Joined:
    Jun 15, 2011
    #4
    How about in comparing a faster i5/i7 with a slower i5/i7?
     
  5. The-Pro macrumors 65816

    Joined:
    Dec 2, 2010
    Location:
    Germany
    #5
    well a buddy of mine who has the 2.4 i5 15" MBP 2010 gets a bit better battery life, somewhere around 20mins more at a CPU load of 25%. these are the first gen ix processors, dont know how it is with SB.
     
  6. calvol macrumors 6502a

    Joined:
    Feb 3, 2011
    #6
    Well, there's no such thing as a free lunch, and it also applies to CPU speed and battery life. The Sony Vaio i7's have pitiful battery life of 3 hours. The new Lenovo x220's with i7 have 8 hours, but with a 9-cell battery. There's probably some gains in efficiency with Sandy Bridge Turbo Boost, but it's having issues on Dell, HP, and Lenovo platforms right now.
     

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