Loud fan noise after replacing iMac hard drive

Discussion in 'iMac' started by Barnum, Jun 28, 2016.

  1. Barnum macrumors newbie

    Sep 4, 2008
    I’m having a problem with a noisy fan in my late 2009 27” iMac (iMac10,1 - OS X 10.11.5). I’ve had my malfunctioning Seagate HDD replaced with a WD Blue 1TB hard drive from a local computer store. After 10 or 15 minutes the hard drive fan is very loud and I believe it’s spinning at maximum speed but the 2 other fans inside the iMac seem to be running fine. I’ve reset the SMC but that doesn’t solve the problem. I can’t send it to a Mac Store because according to the Genius Bar representative my iMac model is considered “vintage” and they won’t repair it.

    Before the hard drive crash I’ve been using smcFanControl and running the fans about 500 rpm faster than normal but now it doesn’t control the HDD fan (although it can control the ODD and CPU fans).

    Will this damage my computer in the long run?
  2. thats all folks macrumors 6502a

    thats all folks

    Dec 20, 2013
    Austin (supposedly in Texas)
    several models of iMacs have a thermal sensor on the factory installed drive. I know if you swap the drive, you need to add a compatible sensor. OWC offers a kit.

    chances are, if this wasn't done, the computer is simply protecting against the lack of input from the now missing sensor and running the fans as a failsafe.
  3. redheeler macrumors 604


    Oct 17, 2014
    ^^^ This. The factory hard drives in the late 2009/mid 2010 iMac models have a built-in temp sensor which normal hard drives or SSDs don't have. I installed the OWC temp sensor after upgrading mine to an SSD and haven't had any issues with fan speed.
    --- Post Merged, Jun 29, 2016 ---
    The fan running at full all the time could cause it to fail prematurely, yes.
  4. Barnum thread starter macrumors newbie

    Sep 4, 2008
    Rather than send money on a thermal sensor kit (I’m saving the funds to replace my Logitech MX mouse and other needed equipment) I’m using an app called Macs Fan Control and it looks like it’s working. Does anybody know what the minimum and maximum temperature for a Western Digital HDD is? (WDC WD10EZEX-00WN4A0)

  5. h9826790 macrumors G4


    Apr 3, 2014
    Hong Kong
    Be careful by using MacsFanConrol. It alter the target fan speed, which means the OS now cannot increase the fan speed even though any temperature is too high. The SMC fan control was altering the minimum fan speed, so the OS can still command a higher target fan speed to spin the fan up when required.

    I didn't own this Mac, but if that fan is purely for HDD cooling, and the Mac can read the HDD temperature without any problem. For MacsFanControl + WD HDD combo, I think it's very reasonable to start with fan speed base on the HDD temperature, min temp 40, and max temp 50, etc. So the fan will spin up accordingly when the temperature getting warmer and warmer. If that gives you loud fan noise, then you may slowly tune up the max HDD temperature, and check what is the usual fan speed and HDD temperature. If the fan is quiet enough, and you want better cooling, you can then reduce the min HDD temperature.

    Since the ambient temperature difference, it's hard for the others to tell you what exact number can gives you both good cooling and quiet fan speed. You have to test it by yourself.

    The calibration process should only cause 10-15min. Not too complicated.
  6. edrodriguez951 macrumors newbie

    Jun 14, 2010
    --- Post Merged, Jul 4, 2016 ---
    I own a late 2009 imac and replaced my HDD with a SSD about two weeks ago. Like "Thats All Folks" stated, the imac has a thermal sensor. I personally purchased the adapter for the thermal sensor from owc, at the time I personally thought that it was a waste of money but from my research there was no way around it. So I bit the bullet and installed it and it works perfectly. My Imac got a speed boost and it's pretty responsive.
  7. tubeexperience macrumors 68040

    Feb 17, 2016
    That digital thermometer sensor is required for normal fan operation.
  8. maflynn Moderator


    Staff Member

    May 3, 2009
    My personal opinion is that the thermal sensor is more important to the proper functioning of your computer then a new mouse. I'd recommend delaying the new mouse and spending it on a new sensor. Just my $.02

Share This Page