coolbook makes MBA rev B slower

Discussion in 'MacBook Air' started by aleni, Oct 12, 2009.

  1. aleni macrumors 68020

    Joined:
    Jun 2, 2006
    #1
    i undervolt my MBA rev B/SSD with coolbook, the temp seems lower, but it makes the air less snappier.

    for example. try to open safari, and then press "cmd W" to close it.. there will be a delay before the safari window closes. I set the voltage to default values, restarted the air, and repeat that task above, BOOM! it closes right as i pressed the W button.

    can anyone confirm this?
     
  2. Consultant macrumors G5

    Consultant

    Joined:
    Jun 27, 2007
    #2
    Captain obvious says:

    undervolt = less power sent to processor = less processing power = SLOWER
     
  3. sanPietro98 macrumors 6502a

    sanPietro98

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    May 30, 2008
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    #3
    That's what you would expect. Coolbook intentionally slows down the processor to reduce heat.
     
  4. aleni thread starter macrumors 68020

    Joined:
    Jun 2, 2006
    #4
    well i thought undervolting just reduces the voltage given, not to make the processor running slower since it's running at the same clock speed.
     
  5. ayeying macrumors 601

    ayeying

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    Dec 5, 2007
    Location:
    Yay Area, CA
    #5
    Shouldn't... I got higher xbench and geekbench scores with undervolting. However since my logic board replacement, running coolbook is counterproductive since the system managed heat better than with coolbook now :confused:
     
  6. sanPietro98 macrumors 6502a

    sanPietro98

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    #6
    Apple spends a lot of time finely tuning the fan controls. I (personally) don't think its a good idea to mess with it.
     
  7. mrscribble macrumors newbie

    Joined:
    Dec 4, 2004
    #7
    I'm by no means an expert but from using Coolbook (successfully), I think you're right. My understanding is this:

    Coolbook has the ability to control both the CPU frequency (clock speed) and voltage (undervolting). Undervolting by itself doesn't have any performance impact (provided you do it right). In fact it will usually speed your computer up (that's been my experience) because the Air underclocks the CPU when it gets hot - undervolting helps it run cooler so it can run at higher frequencies for longer.

    If you don't set up the frequency / voltage settings right though, it may be underclocking when it doesn't need to - for example if you've only set a voltage for 800 MHz, that's all it will run at. It's worth checking your coolbook settings to make sure it's using the highest frequency when under load.
     
  8. Scottsdale macrumors 601

    Scottsdale

    Joined:
    Sep 19, 2008
    Location:
    U.S.A.
    #8
    But every CPU takes undervolting differently and has a different ability to tolerate lower voltages without failure. While one might benefit, another might experience problems even with minimal undervolting. Also, Intel's voltage specifications are set to a range for a chip, and Apple is going with the average specified range and not to an extreme by undervolting each chip. Since all chips vary within the range, it would be time consuming to test each chip against the range. So, a standard MBA setting will work for all chips, in theory. I would increase the voltage and see the differences. Actually, I would remove CoolBook and delete it from the trash bin!

    I personally don't understand anyone using CoolBook on a rev B/C MBA with an Nvidia GPU and Penryn CPU. Surely Apple has maximized a managed environment with components working together in congruence to be efficient, while achieving certain levels of performance, thus equalling exceptional user experience. Messing with it seems counterintuitive to me.

    The thing is the original MBA had a horrific graphics system compared to the Nvidia (5x worse than Nvidia). In addition, it had a higher voltage CPU than the Penryn in rev B/C MBAs. That created massive heat for the tiny system. It was too much power trying to drive terribly inferior graphics resulting in complete failure of the system in many cases even when watching a benign video simple for an iPhone (maybe exaggerating).

    The point is the original MBA was terribly inferior to the Nvidia GPU versions. While CoolBook was successful in the original MBA, Apple corrected the issues requiring Cool Book in the original MBA so those issues were simply not a problem for Nvidia MBAs. The result is an already finely tuned MBA that doesn't need reduced voltage to keep heat lower as the heat is not too great in Penryn/Nvidia MBAs even when hitting the system much harder with CPU and GPU intensive tasks.

    I would personally stay away from Cool Book at all costs UNLESS you own an original MBA.
     
  9. darrellishere macrumors 6502

    Joined:
    Jul 13, 2007
    #9
    Coolbook is great if you need to get the best performance out of revision B/C Air.

    Without Coolbook I wouldn't be able to watch 1080p movies or HD streams!
    I hock it up to my 32" TV that wouldn't be possible without coolbook.

    I don't bother under-volting but un-throttling the cpu is a must !
     
  10. psingh01 macrumors 65816

    Joined:
    Apr 19, 2004
    #10
    The clock speed of a CPU is deteremined by voltage * some multiplier. The speed isn't set to one value.

    Sometimes the multiplier is fixed, so the only way to change the speed is to change the voltage. So overclockers add more voltage, runs hotter, need better cooling. Coolbook is just the oposite. Lower voltage, runs cooler, but at lower speed.
     
  11. ayeying macrumors 601

    ayeying

    Joined:
    Dec 5, 2007
    Location:
    Yay Area, CA
    #11
    Wrong. The speed is determined by FSB or Front Side Bus times Multiplier, not voltage.

    from http://en.wikipedia.org/wiki/Front_side_bus#CPU
     

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