Fan Speed Issue in Mac Pro

Discussion in 'Mac Pro' started by Stairway, Aug 6, 2010.

  1. Stairway macrumors newbie

    Aug 6, 2010
    Hi all,

    I have a 2009 Mac Pro tower (single quad core version) that was working perfectly fine. Last week, I upgraded the CPU to an i7 960, and changed the RAM to non-ECC. Since the upgrade, I have the following happen....

    The system powers on normally, but right about the time of the "chime", there is a serious ramp up in fan speed -- my guess is that something is running full-out, as it is very loud. Problem is, the fan(s) never slow back down.

    At first I thought that maybe I did not seat the heatsink properly, so I re-seated it....I'm sure there is no problem there. I have not yet isolated which fan (or fans) are ramping up so fast.

    The Mac works perfectly though --- both Snow Leopard & boot camped Windows 7 recognize the new CPU & memory. In other words, other than the fan issue, the system works perfectly.

    So, do any of you guys have advice for me in troubleshooting the issue? I know it is not the video card fan, as I pulled that out and still have the same loud fans. Any suggestions would be greatly appreciated....

    Thanks in advance.....
  2. Stairway thread starter macrumors newbie

    Aug 6, 2010
    After some tests, I found that the problem is with the two fans on the bottom front and bottom rear of the case --- on each side of the processor tray. The PCIe and CPU fans are both working normally.

    So now, I just need to figure out why the other two are running so fast/loud....
  3. Stairway thread starter macrumors newbie

    Aug 6, 2010
    Got it figured out. I noticed that the CPU fan was never coming on. Removed the heatsink assembly again, cleaned and re-greased, and carefully replugged everything making sure the CPU fan was getting plugged into its socket. WIth the CPU fan running as it should, the intake and exhaust fans also returned to normal operation.

    So all is well with the system --- runs great!

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