All of a sudden loud PCI Fan!

Discussion in 'Mac Pro' started by Hillskill, Jun 29, 2011.

  1. Hillskill macrumors member

    Jul 12, 2010
    I moved one of our Mac Pros from one location to another today. It came from a noisy server room to a quiet Quality Control booth. Once I had rigged it and turned it on I noticed the fans were extremely loud. Far louder then every single one of our Mac Pro units. I have followed all of the instructions to reset the SMC but nothing helped. We installed SMC controller and iStat menus and sure enough the PCI fan is whirring away at 3070 RPM compared to every other fan being around 600-800 RPM. We have tried to change the default speed in SMC controller but it insists the mininum allowed setting is 3070! We have checked this against our other FCP workstations and they are all happily spinning their PCI fans at 800RPM!?
    I don't know whether this has always been a problem as I would never have noticed the noise when it was installed in an already noisy server room. Now its sitting in a (supposedly) quiet QC booth its not really fit for purpose.

    Anyone have any ideas what the root cause of this issue is and how I might resolve it ?

    Thanks upfront.
  2. DanielCoffey macrumors 65816


    Nov 15, 2010
    Edinburgh, UK
    What cards and drives do you have in the PCI bay of the case? I know an Apple RAID card will cause the fans to run at around 1500-ish (from memory) but not flat out.

    Do you have Apple Care on the machine?
  3. Hillskill thread starter macrumors member

    Jul 12, 2010
    We have an Aja Kona 3G Video card installed in the slot above the GPU. We have Apple Care, the unit is only 4-5 months old.
  4. DanielCoffey macrumors 65816


    Nov 15, 2010
    Edinburgh, UK
    In that case, see ow the machine behaves if you temporarily take out the non-Apple card (and any HDDs that it didn't ship with). See if the noise persists with just the original Apple parts. If it is still running flat out, then it will be an AppleCare call.
  5. Hillskill thread starter macrumors member

    Jul 12, 2010
    This is bizarre. We have DL'd an app that will give a breakdown report of all SMC settings. The PCI fan is set to a minimum of 3070!!!
  6. kirreip macrumors regular

    Feb 11, 2009
    have you tried resetting the System Management Controller (SMC)?
  7. Darth.Titan macrumors 68030


    Oct 31, 2007
    Austin, TX
    Did you even read the OP?
  8. Hillskill thread starter macrumors member

    Jul 12, 2010

    Yes followed all instructions to the letter but no joy. There doesn't appear to be an SMC reset switch on the logicboard either :confused:
  9. nobiggiestudio macrumors newbie

    Jun 7, 2011
    Are you talking about a fan on a PCI bay attached device?

    Then it might overheat...take it apart at look at it.
    Is the thermal compound and thermal pads dried out?
    Is it clogged with dust?
    It might be the problem as the themp. is just to high to let your guys tweak the speed. As it really try to stop your guys from frying the card.
    If so:
    clean it all with a brush, wash it with rubbing alcohol.
    Apply new thermal compound and cut some small pieces of copper as the level not being high enough because the thermal pads is thick.
    Put it together and see if it worked.

    If it the fan still screaming like a devil!
    Unplug the fan from the PCI fan and run it of an molex and a manual fan controller bought at some electronic shop. Cost like 7 bucks or less.

    If your talking about the fan in the front grill cooling the PCI cards:
    Unplug the fan from the PCI fan and run it of an molex located in the DVD cage.
    If your using both DVD devices you could buy an molex split cable from 1 molex to 2 molex.
    Also buy a manual fan controller at some spare part electronic shop.
    Cost like 7 bucks or less. And attach the cables to the fan.
    You could replace the unit at any apple repair center if you don't want to mess with the machine your self.
  10. dknightd macrumors 6502

    Mar 7, 2004
    One of my 2010 mac pros goes nuts like that. Has happened a few times since I got it. I found that rebooting it, or putting it to sleep then re-waking, "solved" it. Stupid fan only seems to know two speeds - idle and full throttle.
    Just happened again today - was a little warmer than usual, and I asked it to do something - the temperature sensors don't seen to show a problem, just that one fan goes berserk.

    If it was full throttle all the time I'd take it in. But if a reboot, or sleep, fixes it, they will find no problem . . .

    Try putting your mac to sleep. wait one minute. wake it back up. It is a PIA but as long as it happens infrequently I guess I can deal with it easier than taking in for repair and being told there is no problem. Of course you might have a different problem, or you might be lucky and have a persistent problem they can actually diagnose and fix.

    Let us know what you find.

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