Mac Pro ATI5870--uneven fan sound when idling..any thoughts?

Discussion in 'Mac Pro' started by ejosepha, Mar 9, 2011.

  1. ejosepha macrumors 6502

    Jan 12, 2009
    I recently had a noise issue with my new Mac Pro with the ATI RAdeon 5870 card. There was a lot of noise when the fans cranked up. Apple techs here in Paris took the machine and said they put it under an Apple analysis and test over night and now the noise that they heard themselves is now gone. They replaced nothing. They repaired nothing. Though I can hear the fan on the graphic card increase in spin noise when it rises above idle, which I presume is normal, it is somewhat better than when they took in the machine for repair. However, when the computer is idling and the graphic card is idling under no load I can now hear more of an uneven fan noise, which is disturbing. It's as if you can hear the fan changing its tone or tonality, moving up and down in tone as it idles.
    It's not all of the time, but most of the time when there is no load on the card. Like an uneven humming under lowest fan speed.
    Doe anyone else hear this symptom? Is it normal as the fan or bearings are running at their slowest? Everything else so far works ok graphically with the card. (I had a MBP 17 that made noise when idling once and they replaced the two fans in the back and the noise was gone.) I realize this is a high performance graphic card and I do work in a quiet space, but if replacing the card would net me a more even sounding working environment I would risk it. If not, then c'est la vie.
    Thanks for any advice.
  2. Johnf1285 macrumors 6502a


    Dec 25, 2010
    New Jersey
    I can comment on the uneven fan sound for the intake and exhaust fans. I notice this when the fans are running at their lowest speed. I also noticed that these fans appear to be somewhat normal computer fans, housed in a fancy plastic mounting bracket that fits within the cpu cooling tunnel. I am going to investigate further, but a small purchase of higher quality fans and some simple splicing may yield a cooler and quieter operation. As far as the graphics card, I have no feedback on the 5870 as I have the 5770, and it sounds pretty normal to me.
  3. ejosepha thread starter macrumors 6502

    Jan 12, 2009
    When I look at IStat Pro the intake and exhaust fans remain at their lowest speeds of about 599 when the graphic card kicks up speed, and when this occurs the unevenness disappears. So for me it seems to be associated with either the psi fan or the graphic card fan itself, or the fan noise you are referring to is drowned out by the increase in graphic card fan noise. Hard for me to tell. When I put my ear to the lower fan in front and back I don't sense that this unevenness is coming from them.
    Would like more input, if possible from other users.
  4. ejosepha thread starter macrumors 6502

    Jan 12, 2009
    I hear what you are referring to a little bit but would very much like to know if others have any unevenness of fan noise when their Mac Pros are idling with no load. And where they think this effect is emanating from.
  5. handheldgames macrumors 65816


    Apr 4, 2009
    Pacific NW, USA
    Most noise in my 2009 comes from the pci bay fan... it's too small of a fan.
  6. derbothaus macrumors 601


    Jul 17, 2010
    At idle my 5870 fan never changes speed. It only changes at post (boot) and when gaming.

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