Power down one core manually? (MBP)

Discussion in 'PowerPC Macs' started by jesaja, Mar 10, 2006.

  1. macrumors member

    Joined:
    Sep 15, 2003
    Location:
    Lichtenstein
    #1
    Hei!

    I've heard (where, I don't remember) that you could manually power down one core of the MBP to save power when on the road.
    Now that I got my 'Book today (yay - I recieved it as a replacement for a 15"Powerbook!) I've looked for it, then searched google. etc - and nowhere I can find anything how to do it...

    So - does it work? And if yes - how?

    Thanks a lot, greets,

    jojo
     
  2. macrumors 68040

    Koodauw

    Joined:
    Nov 17, 2003
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    Madison
    #2
    Well Im sure there is another way, but if you insert the install disk and install the CHUD tools, it will allow you to do this. I just did the custom install and just installed the CHUD tools.

    It will add another option in your System preferences called Processor , and you can put an icon in the menu bar. Thats what I did.
     
  3. macrumors 65816

    AlexH

    Joined:
    Mar 7, 2006
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    Hot Springs, AR
    #3
    So what kind of battery life are you getting with one core instead of two? I'd be interested to see your results with one core and two.
     
  4. thread starter macrumors member

    Joined:
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    #4

    Wow - that was a fast answer! Thanx a lot! I'll try that. Didn't hink of installing additional things off the DVDs yet...:rolleyes:

    jojo

    PS: well - I just have it for 5 hours now, so... *jumping*
     
  5. macrumors member

    Aramis

    Joined:
    Feb 25, 2006
    Location:
    East Coast
    #5

    Besides battery life, is there any reason you would want to power down one core? I am assuming this would slow all processes?

    Just wondering as I am very new to the Core Duo technology (so I should probably read some more before asking these questions:) )
     
  6. macrumors 601

    ITASOR

    Joined:
    Mar 20, 2005
    Location:
    Oneida, NY
    #6
    What choices are available in Energy Saver>Options on the MBP? (Meaning like, most laptops have Auto, Highest, Reduced.)
     
  7. macrumors 68030

    homerjward

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    #7
    battery life is pretty much the only reason, except possibly heat issues which sort of goes with battery life.
     
  8. thread starter macrumors member

    Joined:
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    #8
    yeah - it works! (Though it was not so easy to find - didn't know these belong to the XCode Tools)
    By the way - the monitoring panel is really cool. And the ability to switch off one core with one single click! :D

    jojo
     
  9. macrumors 6502a

    mdavey

    Joined:
    Nov 1, 2005
    #9
    There are mixed reports about the results of doing this. On PCs, it actually puts extra load on the remaining core such that operations take more than twice as long as with both cores up and thus battery life is negatively impacted. I suggest performing some benchmarks/tests to confirm that battery life is actually extended by powering down one core.
     
  10. macrumors demi-god

    Joined:
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    Virginia Beach
    #10
    I wonder if some folks think that the second core is a second, full-sized processor sitting in their MBP, and that by turning it off they'll save 50% of the processor power. :confused: :eek:
     
  11. macrumors 68040

    Koodauw

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    #11
    that would be a dual processor system. I just turn it off for comparison purposes.
     
  12. thread starter macrumors member

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    Lichtenstein
    #12
    Hey - I'm not stupid. But away from power outlets I'm trying to squeeze out every single minute of my notebook. And so I wanted to try this, too.

    And yes - It brings me only about a quarter of an hour, but hey - better than nothing. And 'on the road' I don't need the 'extra power' of the second core, even the first idles ;) around at ~10-20 %...

    jojo
     
  13. weg
    macrumors 6502a

    weg

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    #13
    According to Tom's hardware there's virtually no difference. The processor is not the only piece of hardware that's drawing power..
     
  14. macrumors demi-god

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    #14
    Fair nuf! Definately didn't mean to imply that you were stupid. Sorry if you took it that way. :)
     
  15. macrumors 68020

    yippy

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    Chicago, IL
    #15
    Another reason you might do this is as a developer to see the performance of your app on a slower system.

    That said I have also heard that powering down one core has negligible impact on the battery.
     
  16. macrumors 68020

    Krevnik

    Joined:
    Sep 8, 2003
    #16
    In my case, this is true... I have seen the battery life remain about the same with one or two cores.
     
  17. macrumors 6502a

    Grokgod

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    #17
    I want to disable the second core to reduce the heat that is coming from the ALU! Since I mostly use the laptop for typing, the second core is of little value to me, usually.

    Does anyone have any experience with reducing heat by disabling the 2nd core?

    And I sure could use a pointer to installing the CHUD and getting the talk about option.

    I tried downloading the chud from APPLE and after installing had NO options to disable or anything new in the System preferences.

    TIA:D
     
  18. macrumors 68000

    Joined:
    Mar 12, 2006
    #18
    I am using an iMac, but it doesn't to seem to make a difference. Also, It says it is using a Pentium M:confused: ? What the hell. Probably is the closest processor. So thats why the MBP gets so hot...its a pentium:D But the CPU NOISE actually decrease. to MBP users, disable one core.
     
  19. macrumors 6502a

    Grokgod

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    #19
    I dont think that its a Pentium M.

    Its a yohan or something like that.
     
  20. macrumors demi-god

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    #20
    I think I've seen some posts where folks said that running with just 1 core causes that core to run higher/hotter than when the load was distributed over 2 cores.

    I'll see if I can find that post...
     
  21. macrumors 68000

    technicolor

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    #21
    My MBP runs way cooler with the 2nd core disabled, its very noticeable the difference.
     
  22. macrumors 6502a

    spencecb

    Joined:
    Nov 20, 2003
    #22
    For all of you that think shutting down one of the cores will give you extra battery time, you are WRONG.

    One of the best features of the Intel Core Duo chips is that it is ver efficient in conserving power. By shutting down a core, you are taking away that ability from the processor.

    When I shut down a core, my battery time remaining instantly drops by about 40 minutes. Obviously, not a smart thing to do.
     
  23. macrumors newbie

    Joined:
    May 1, 2005
    #23
    Although it's counterintuitive, using only 1 core will make it run hotter and reduce battery time. I don't know why, but that's what happens. I installed CoreDuoTemp and found that the temp was higher with only one core and you can read here for battery tests that show that it reduces battery time.
     
  24. macrumors 68000

    Josias

    Joined:
    Mar 10, 2006
    #24
    Just a warning before powering down: You will be degraded to around 1.2 GHz Core Solo instead of 1.83-2.16 GHz Core Duo. This will make it even slower than the Mini... Though it will save a lot of battery.
     
  25. macrumors 68000

    technicolor

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    #25
    It doesnt save battery time, as a matter of fact it killed my battery time, but it ran cool enough to sit on my lap with nothing underneath.
     

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