103*C and 2300 RPM fans, UMBP

Discussion in 'MacBook Pro' started by puma1552, May 12, 2009.

  1. puma1552 macrumors 601

    Nov 20, 2008
    I was taxing my Late 08 15.4" UMBP last night by downloading a two gig movie from iTunes while simultaneously watching an "adult" film of the flash variety, on a 24 inch ACD at full screen.

    Happy with myself, as well as my purchases allowing me to do such things, I finished my adult feature and got up to exit out, when I looked and saw SMC reporting a 103*C temp with the fans only spinning at 2300 rpm.

    I have SMC purely for monitoring purposes, and leave the stock fan speed at the 2000 minimum. I was just surprised that the system management would let the computer get that hot and still keep the fans at such a low speed, when I know it's gotten up to 4500 rpm at 90*C other times.

    Thoughts? I immediately used SMC to boost both fans up to 6000 until it came down to a much cooler temp.
  2. alphaod macrumors Core


    Feb 9, 2008
    Mine does the same thing; temperature goes up but the fan only spin up when it hit around 95ºC.
  3. J the Ninja macrumors 68000

    Jul 14, 2008
    The fan controller appears to either be on a delay of some kind, or waits for another temp much higher than the normal CPU target temp before speeding up. Either way, it's probably to avoid triggering the fans for brief temp spikes. Mine waits to speed the fans until around 95, but once they come on, the system seems adamant to keep the CPU temp in the 80-85 range. Strangely, when doing a long network file transfer last weekend, they eventually spun up to around 2400rpm or so, even though nothing ever went past 80C. Also, it seems to only want to vary the fans about .25% at a time, so they take a bit of time to spin up.

    In short, there are a lot more variables involved in the fan control than just target and max temps.

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