4.1 to 5.1 Upgrade - Fans at full speed. Help!

Discussion in 'Mac Pro' started by unununtitled, Aug 6, 2015.

  1. unununtitled macrumors newbie

    Aug 6, 2015
    I decided to do the 4.1 to 5.1 and 8-core to 12-core upgrade today -

    Both CPUs installed, both CPUs' showing (2 x 6-core 3,46 Ghz) all RAM sticks showing, BUT the fans are running on full speed!! What to do now..?, I've tried tightening and loosening the screws on the heatsink several times, but still full speed on the fans!

  2. box185 macrumors member


    Sep 12, 2013
    Did you upgrade with lidded CPU's? If so, did you clip the plastic connectors free from the heat-sink and get those hooked up?
  3. JazzyGB1, Aug 7, 2015
    Last edited: Aug 7, 2015

    JazzyGB1 macrumors regular

    Jan 18, 2002
    I have performed the same upgrade (except it was 2 x 2.93 for me) - it's great when it's done! :)
    As you're finding out though, it's not an exact science which makes the upgrade quite tricky.
    The full running fans usually means that the fan cable from the heatsinks isn't seated properly.
    Have a look at this fantastic video here as a useful guide...

    The heatsink fans are mentioned at 4m 12s into the video.
    Hope this helps
    Good luck! :)

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