iMac 27" HDD Fan full speed - random

Discussion in 'iMac' started by iDutchman, May 14, 2013.

  1. iDutchman macrumors 6502a

    May 9, 2010
    Amsterdam, NL

    I have an iMac 27" Late 2009 that got it's Seagate HDD replaced by Apple 6 months ago (replacement program).

    However, the HDD Fan ramps up to the full speed (5500RPM) for no reason. This happens very random (say 10 minutes of using from a cold boot).

    The Hard Drive sensor functions and it runs cool (40 degrees centigrade).

    Why does it still go to full speed even though it measures the right temperature for the HD? I tried a clean install, smc and pram reset.

    Advise or suggestions would be greatly appreciated!
  2. Dadioh macrumors 65816


    Feb 3, 2010
    Canada Eh?
    Sounds like it could be an intermittent sensor. Try running Apple Hardware Test (AHT) and see if it finds anything. AHT is on the applications installation DVD that came with your iMac. Hold down the "D" key while booting with the application install DVD in the drive. Run the extended test and see if it comes up error free.

    However, if it is intermittent then it might take more than 1 run to find it.
  3. iDutchman thread starter macrumors 6502a

    May 9, 2010
    Amsterdam, NL
    Thanks for the information. The installation CD's I don't have anymore. I used to have a 27" Thunderbolt Display + rMBP setup but traded the display for this iMac 2 weeks ago (no extra money involved, great deal!).

    I installed a program called SSD fan control that allows the system to base it's fan speed on the S.M.A.R.T. status of the drive and not on the internal sensor (the unfamous sensor). Now, it runs like it should (1100-1200RPM with 38 degrees).

    However, I will be opening the iMac up today to install an SSD in a optibay I have lying around. I will see if I see anything odd.

    I'll keep you posted.

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