Can somebody tell me at what point the fans should 'speed up'?

Discussion in 'iMac' started by Siriosys, Feb 3, 2009.

  1. Siriosys macrumors regular


    Dec 24, 2007
    New Zealand
    Hi all,

    I have a 2007 2.4Ghz iMac running 10.5.6

    I have previously been running SMC Fan Control with the HDD fan speed cranked right up to 2000, but I decided to find out what would happen without SMCFan Control running.

    I'm using the latest version of iStat and have noted that the Fans are running as follows:

    In my office the AMBIENT Sensor gives a reading of 27 Degrees C
    CPU Fan speed - 1200
    HDD Fan speed - 1200
    OPT Fan speed - 700

    Well, the temp on the HDs are as follows after 10 minutes without SMC Fan Control running:

    HD BAY 1 51 Degrees C.......and climbing - was previously 48 Degrees C
    HDD itself is 50 Degrees C

    I know that the SMC CAN increase the Fan speeds as I'm able to run the diagnostic software which seems to run the fans at various speeds as part of it's tests. All of the tests pass.

    Now my questions are as follows:

    Are my expectations too high in assuming that the fans should be kicking in ABOVE their defaults to bring the temp down on the HD given the room temperature? To me, 50 Degrees C is very hot and in fact at the upper level of the recommended spec as set by Western Digital - as per their website.

    What 'sensible' tests can I perform to increase the system temperature to a point at which the SMC should increase the fan speeds WITHOUT the use of third party software such as SMCFan Control?

    If the testing above proves that the SMC is NOT doing what it should, what would be my best options - aside from installing SMC Fan Control again?

    I really don't fancy cooking my HD - And heat IS their Nemesis


  2. AlexisV macrumors 68000


    Mar 12, 2007
    Manchester, UK
    Best option is to stop being paranoid :D

    The fans should kick in as a short term emergency cooling system. On a hot day, without much air circulation, the fans may rev up for 3 or 4 minutes and sound like a vacuum cleaner.

    At all other times the Mac will be gently adjusting its speeds. Overall certain parts remain hot. There's nothing you can do about it and personally I think there's no need for worrying.

    Have you considered that WD might just be claiming a max of 50C to reduce warranty claims? They'll receive hundreds of warranty claims each month - much easier to refuse them if they claim they've been running beyond their operating window.

    I've yet to hear of an alu iMac hard failure.

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