Fan Speed to loud!

Discussion in 'Mac Pro' started by ~Lukasdp, Nov 16, 2010.

  1. ~Lukasdp macrumors newbie

    Nov 15, 2007
    My new MacPro is less then a few weeks old. straight out of the box the fan in between the DVD drive and the power supply goes rather loud after 20 seconds of the machine powering on, and stays loud. Iv'e reset the SMS and still no change, recently updated the 10.6.5 and again, no change.
    any thoughts on what might be causing this? no programs are running that would need such a high fan speed, the machine does this of its own accord.

    thanks for your help!

    Attached Files:

  2. timbloom macrumors 6502a


    Jan 19, 2002
    I've heard of the SATA cable on the optical drive rubbing up against the psu fan/enclosure. You may pop the optical bays out and try flexing or repositioning the cables a little and see if it improves. If it's still making fan noise and you are sure they aren't touching you might drop it by an apple store for further evaluation.
  3. timbloom macrumors 6502a


    Jan 19, 2002
    It's likely that a temperature sensor in the PSU is unplugged or malfunctioning also. They usually default to a failsafe full-on mode if that happens to protect hardware.
  4. ecorb macrumors newbie

    May 22, 2012
    I've been trying to correct the full-speed fan syndrome on my mac pro (2008 2.8 quad core) for months now. I finally downloaded and installed iStat, then saw that the "Northbridge" temperature was way higher than any other temp (it typically ramps up from 140 to 259F).

    What fixed it finally was simply disconnecting and reconnecting the northbridge heatsink-to-motherboard connecter. It is a simple two-prong connecter just left of center in this photo: You can perform this without tools, but tweezers or needle-nosed pliers may help. There is no 'latch'.

    Perhaps a weak connection there led to erroneous resistances and a false temperature reading.

    The connecter is easily accessible by just taking the side panel of the computer off and removing the video "card".

    The Northbridge temperature is now stable around 122F, more in line with the other temps.

    It's kind of embarassing what I went through in the way of troubleshooting, but let's just say I wish I'd started with iStat six months ago.

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