Processor power management in W7 on new MBP (13)

Discussion in 'Windows, Linux & Others on the Mac' started by sephstyler, Mar 11, 2011.

  1. sephstyler macrumors newbie

    Jul 13, 2010
    Hey all,

    just moved from the 2010 13" MBP 2.66 to the 2011 i7 version.

    Just installed W7 Pro via bootcamp, and was setting windows to the way I like it, when I noticed that, it appears that the processor power management that comes with windows didnt seem to be limiting the processor power...?

    I used geekbench to measure the performance on my modified "balanced" setting (25% processor), and got a score within 10% of my score on "High Performance" (100%).

    Then using various apps, including "speedfan", I saw that all 4 cores were hitting 99% usage under geekbench when using the balanced setting...

    I didnt notice this on my 2010 MBP....

    does anyone know whats going on here? is there a workaround?

  2. vistadude macrumors 65816

    Jan 3, 2010
    Balanced is the best setting for a laptop. It will use 100% of CPU power whenever anything needs to run, except for background processes. Thus it uses full power when needed. It uses reduced CPU clockspeed when you aren't doing anything.

    The high performance setting isn't needed except for some old games which change FPS erratically.

    Power saver will throttle down the CPU power always. I wouldn't recommend this unless you're getting very low on battery life.
  3. sephstyler thread starter macrumors newbie

    Jul 13, 2010
    Appreciate that vistadude, but I think you misunderstood the question.

    I've modified the advanced settings of the power profiles to limit the CPU clock speed under "balanced"

    this used to work fine, but on this new MBP, clock speed seems always set at the 2.7 ceiling. I understand how it will only use the full clock speed when required, but I wanted to limit it anyways to get max battery.

    as an example, my 2.66 Core 2 duo MBP 13 (2010) can get approx 5 hours under W7 with a reasonable power scheme, but under the same settings for the new MBP, I can barely get 3. The difference is that the 2010 can "throttle" the CPU and the 2011 cant....?
  4. vistadude macrumors 65816

    Jan 3, 2010
    Ohhh, I see what you mean. Hmm that's very strange, because it wouldn't even be driver related. I wonder if it's a hardware limitation. Maybe you can run a similar test under Mac OS and see if you are stuck at the max Mhz?
  5. sephstyler thread starter macrumors newbie

    Jul 13, 2010

    Good idea, im not familiar with what program I can use in OSX to do that, any suggestions?
  6. vistadude macrumors 65816

    Jan 3, 2010
    iStat nano is a neat widget you can add to the dashboard, although I must admit, the CPU percentage has 4 different numbers, so i'm not sure which is the real one!
  7. sephstyler thread starter macrumors newbie

    Jul 13, 2010

    After a bit of tinkering it appears (in CPU-z) that in W7, at idle, the processor is running approx 800mhz. but with almost ANY activity, it shoots back up to 2.7GHz.

    Even with the windows power plan set to say, 50% of processor power, or even 30%, it will still go at 2.7, and 1.06V volts.

    Hence I dont know what is the issue, but either the boot camp drivers or the hardware doesnt talk to the power plan settings properly.

    Anyone have any ideas? I get "normal" battery life in OSX, but <3 hrs in W7 (with almost everything turned down/off), and its definately the processor taking all the juice.

    Tempted to return this MBP now, as my 2010 13" 2.66 C2D COULD limit the processor power, and I could get 5~6 hours from it in W7! this is HALF!
  8. thejadedmonkey macrumors 604


    May 28, 2005
    You're better off considering yourself lucky you once owned a mac that got almost full battery life running Windows. My MBP gets 1/2 the battery life in Windows Vista, and 1/3 the battery life in XP (7 is unsupported by Apple).
  9. ninja2000 macrumors 6502

    Dec 16, 2010
    Thats very strange. I don't own a 2011 13" but it works on my 2011 17"!
    I set my max cpu to 90% which caps the cpu at 2ghz. I do this to minimise heat/noise rather than looking to improve batt life. It takes a good 10-15watts of my load output.

    Your other option is to try throttlestop ver 3. Although designed to stop your laptop using lower multi's it also gives you the option to limit the multi's manually.

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