11" i7 Fast fans for a long time

Discussion in 'MacBook Air' started by MirroRobin, Aug 4, 2011.

  1. MirroRobin macrumors member

    Joined:
    Nov 10, 2008
    #1
    I've been having a problem with the fans with my 11" i7 that I've gotten 4 days ago. I'm running a 27" cinema display, I don't much CPU intensive and my CPU is usually 95% idle and fans are usually quiet. Every time I start doing something more CPU intensive like running iTunes visualiser or run handbrake the fans start spinning a lot faster, often up to its 6500rpm max.

    The problem is not that the fans start running, but the time it takes for them to ramp down to their base 2000rpm after the CPU intensive task is done and the CPU has cooled off already. Fans just keep on spinning fast until I leave it completely idle for a about 10-15 minutes.

    It has something to do with the room temperature at the location where I primarily use my macbook, which is in the attic of my house where it gets quite hot (30-35c) on warm days like today. In order to test this hypothesis I set up a fan behind to computer to feed it some cool air. Fans were spinning at 6500rpm before setting up the external fan and afterwards they instantly started to slowly but steadily ramp down to 2000rpm again.

    Although it is good news that I sort of figured out the source of my problem, the question remains whether it is normal for a computer to take a very long time to ramp down the fans after finishing a CPU intensive task and having cooled off internally already (according to iStat), but while getting fed warm air. Please note that this only happens after doing a CPU intensive task. If I don't do anything CPU intensive all day, the hot air doesn't bother my computer at all. Any ideas whether the effect air temperature has on my MBA is normal?
     
  2. lukekarts macrumors regular

    Joined:
    Mar 16, 2009
    #2
    Yes, it's pretty much normal. The Core i processors run about 10 degrees C warmer at idle, and typical temperatures when at 90%+ are 88-90 degrees C.

    The other thing to factor in, is that when they get the opportunity, they TurboBoost to 2.7Ghz which naturally increases the temperature, at which point they rely on fans to cool, or they stop boosting and/or shut down cores.

    The only complaint would be, I don't think they need to boost as much as they do, as it does make the fans play catch up quite often, but there's no technical fault to worry about.
     
  3. MirroRobin thread starter macrumors member

    Joined:
    Nov 10, 2008
    #3
    The thing it though that they keep on running really fast long after the CPU has cooled down already. I've had instances where the CPU load was low and CPU temperatures already down to 65c, but the fans were still blasting at 6500rpm for a long time (5-10 minutes at least). Question is whether 30-35ºC air in a warm room is supposed to have such an effect on the fans.
     
  4. MRU Suspended

    MRU

    Joined:
    Aug 23, 2005
    Location:
    Other
    #4
    Reset SMC


    To reset the SMC or the System Management Controller you have to do the following.


    Turn the computer off. Make sure the laptop is plug in the power supply and the power cable is plug in a power source. Press and hold the following keys at the same time the ‘Power’ button + ‘Shift’ key + ‘Option’ Key. Release the keys and turn the Macbook Air laptop on by pressing the power button again.
     

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