How does Macbook Pro manage fan speed?

Discussion in 'MacBook Pro' started by RELOAD911, May 5, 2010.

  1. RELOAD911 macrumors member

    Dec 12, 2009
    Hey there Macbook Pro owners! I'm trying to figure out how does the cooling system in MBP's work. I've been using FanControl for quite a while (the one by Lobotomo), it does the job pretty straightforward - just dynamically changes the fan speed. But when I was using default settings the fans were at low speed even when temp was around 80C. Any idea what default settings for Apple notebooks are? I mean, lower and upper thresholds, how and when does it kick in the fans etc. Appreciate your help in advance! BTW I've got MBP1,1 in case it matters.
  2. yertle macrumors member


    Mar 13, 2010
    I don't know but the new MBP runs a lot cooler than the 13" MP (2007 Santa Rosa) does. Haven't even heard the fans on the MBP kick in yet. Hope that helps a little.
  3. TuffLuffJimmy macrumors G3


    Apr 6, 2007
    Portland, OR
    1,1 means it's a first generation.

    One of the joys of owning a Mac is not having to worry about the computer itself. Why would you need to worry about the upper thresholds of the cooling system? The machine will work the way it's been designed to, utilities to control fan speed are unnecessary. If you are actually having problems with the fan speeds I recommend taking the machine to an Apple Store or dusting the internals.
  4. RELOAD911 thread starter macrumors member

    Dec 12, 2009
    Yea, I know.

    That would be true, but I need to run my system cooler so I can work comfortably (macbooks can get pretty hot, ya know) AND I also need a 99% crash-proof system. I don't care what Apple say about Flash, 90% of my crashes (though there aren't a lot of them generally) are related to heat. Sometimes I need to render some stuff and MBP is getting very hot (at relatively acceptable temperatures though) considering the fact that both GPU and CPU are being loaded 100%.

    So, what is this all about? Well, I actually HAVE solved the heat problem, it's not a problem anymore. But I want to know how does original Apple cooling software part work to understand the machine better and pull some more juice out of it. Knowledge is power, don't you agree?
  5. TuffLuffJimmy macrumors G3


    Apr 6, 2007
    Portland, OR
    Apologies. Obviously you know. I was informing yertle, considering yertle's comment was entirely non sequitur.

    Apple controls fan speed by default based on workload and current internal tempertures. What sort of crashing are you experiencing due to heat? What is your work environment and why do you need a cool machine to work comfortably? Surely you're not loading your CPU and GPU while holding your Macbook in your lap, are you? That would be a silly and nearly surefire way to destroy your computer.
  6. RELOAD911 thread starter macrumors member

    Dec 12, 2009
    The crashes are pretty simple - when GPU temps are getting close to 67-68C the system becomes very unstable. Cooling it with FanControl and reapplying the thermal compound (Apple guys suggest to replace Logic Board for 500$, duh) completely solved the problem.
    My work environment varies, sometimes I work at home and need to leave it working for quite a while (up to 12 hours straight), sometimes I need to tweak some stuff during the meeting. I make graphics/visual effects so every now and then I need CPU and GPU power. That makes a laptop quite hot.
  7. davidlv macrumors 65816

    Apr 5, 2009
    Kyoto, Japan
    Actaully I think my MacBook Pro has a very good temperature control system, :cool::apple::cool: but I don't especially like how it is implemented. Policy seems to be the key word here. Apple engineers are obviously very capable in their field, but what are their priorities and /or directives? I assume they depend on the Intel data for a viable operating heat range and adjust the fan control sytem to keep the heat within that range. Apple, marketing department?, on the whole seems to put a higher priority on keeping their laptops quiet, compared to cool. So we have users like Reload... who would like a cooler machine, and is willing to have the fans kick in earlier, and users like TuffLuff... who trusts the engineers' decisions on this matter, and is willing to deal with the heat in an informed manner. Well, I personally think that policy of placing "quiet" above "cool" is not for me, so I installed smcfancontrol to keep the heat somewhat under my personal tolerance level. I have found that ambient temperature really makes a difference, or in other words, this mid-2009 2.53GHz C2D with one fan has an operating temperature at least 10-15 degrees higher in summer than in winter. Using the standard 2000 rpm, the machine gets really hot (quickly rising to 60-70C) when both cores are being used close to maximum - and Apple's policy does not make the fans kick in until about 80C, which is far above my tolerance level.:eek:
    From my experience, 2,500-3,000 is almost silent, I don't have good hearing, but even at night in a very quiet room I can not hear the fans unless I get very close to laptop's surface. 4,500 is however, really loud. Your experience may vary here, as every environment is different.
  8. Tanegashima macrumors 6502

    Jun 23, 2009
    Macbooks (and all apple computers) have a separate system to manage such things:

    The System Management Controller (SMC) is responsible for many low-level functions on Intel-based Macs. These functions include:

    Responding to presses of the power button
    Responding to display lid opening and closing on portable Macs
    Battery management
    Thermal management
    The SMS (Sudden Motion Sensor)
    Ambient light sensing
    Keyboard backlighting
    Status Indicator Light (SIL) management
    Battery status indicator lights
    Selecting an external (instead of internal) video source for some iMac displays

    It operated with a separate microprocessor.
  9. RELOAD911 thread starter macrumors member

    Dec 12, 2009
    So I did some tests and figured a little bit out and I'm about to share it just in case anybody needs this.

    It seems that all the way up from 60 (just a guess about this one) to 90C the system slowly tweaks fan speed from 1000 to 3000 rpm. After temp reaches 90, the step changes and system starts raising the fan speed by 100 rpm/second until the temp gets below the upper threshold (which is 90C). At least I think that's how it works.

    Hope anybody could use it. I did ;)
  10. npaisnel, Jan 2, 2014
    Last edited: Jan 2, 2014

    npaisnel macrumors member

    Jun 23, 2013
    Yes..this is a fan question..exactly the same as the OP's original tittle..but I want to give the background first.

    I have just acquired (free) a MBP 3,1 A1226 15 inch version with the nvidia 8600 chip.

    It was dead... been that way in a cupboard for 3 glitches..
    I booted from USB and it worked fine ..immediately...
    Installed Mavericks from USB.

    Great for two days..then graphics glitches again and USB boot did not work

    This is when I found out about the nvidia issue. Too late for the free logic board swap so...

    200deg C for 8 minutes did the trick....for now. New thermal paste and cleaned the fans and heat tubes

    I have installed iStat Menus and have set it to display temps and fan speeds

    Without changing any fan settings within iStat menus and running multiple threads of
    "yes > /dev/null &"
    the temps show as CPU die getting up to 94 deg C

    Yet fan speed never goes above 2800 rpm even if left running for 10 -15 minutes. [Edit seeing 3200 rpm now]
    So that got me wondering about the default speeds and temps 'hardwired' in to the Mac.
    OK, so one would assume that the Apple designers are keeping the CPU/ Memory etc within Intel design specs...but 94deg C does seem rather hot.

    is there any advantage in running cooler ..I'd have thought longer life...but ??

    There are all these utilities designed to speed up the who is right?

    Ooops.....just about to post and the screen has scrambled and come back with frozen keyboard guess I have answered my own question..extended heat not good ;)

    Power button hard 'off ' shut it down and normal re boot. I guess this is the Nvidia graphics chip issue.

    But comments welcome
  11. bds120 macrumors member

    Nov 26, 2013
    Well you are in the sane category as me. I have 2008 myself that I decided to do preventative maintenance on just to stay away from the graphics issue. I took entire laptop apart and cleaned everything with alcohol and reapplied Arctic MX-4 thermal paste before I ever had any issues. Then I used canned air to spray dust off fans and such. I use smcfancontrol now with the default set to 3200 rpm.
    I get no numbers higher than 145 degree F when running YouTube, monopoly games, and whatever else at the same time.

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