IOH Heatsink error causing fan spin up to 4000RPM

Discussion in 'Mac Pro' started by leifislive, Sep 30, 2012.

  1. leifislive macrumors newbie

    Dec 12, 2006

    I am referring to this thread

    I upgraded my GPU to the ATI 5870 and observed intermittent Booster 1 fan spin ups to 4.000 RPM. I then thought it is an error due to the ATI, but using iStat I observed, that this fan speed up only happens, when the IOH Heatsink temperature suddenly exceeds 120°C for some seconds - running programs or in idle, independent of the GPU.

    SMC reset didn't work.

    So, I think the IOH Heatsink Temperature Sensor is broken?

    Thanks for help!

  2. Spacedust macrumors 6502a

    May 24, 2009
    It should be about 70°C
  3. Inconsequential macrumors 68000

    Sep 12, 2007
    Sounds like your IOH heatsink connection is dodgy.

    Reseat your CPU heatsink?
  4. leifislive thread starter macrumors newbie

    Dec 12, 2006
    I got it

    MacVidcards (from the other thread) and Concorde: you had the right idea .. It is always the weakest part that breaks first... :)

    One of the two wires from the female jack "jd900" (if I read that correctly - it connects to something under the heatsink - I didn't dare to look) had a loose contact to the plug. I just made it stick again in its supposed to be place, and now things apparently work.

    BTW.: I "demystified" the 1066MHz RAM vs. 1333MHz RAM issue for my self I was wondering about. Having read this thread per chance (, I just used 3 bricks. Now I have 12 GB running at 1333MHz instead of 16GB running at 1066MHz, yet only 1286 score in Heaven 3.0... may be different processor board versions were used?

    I would heartfully thank all those reading my posts and those answering them. Of course anyone, who had posted on similar but somehow different issues, which finally made it possible for me to downtrack my problem and apparently solve it !!!!!!!!!!!!!!! :D:D:D:D:D:D:D

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