To all my buddies with fan problems (there's hope!!)

Discussion in 'Mac Pro' started by Greenbird600, May 29, 2008.

  1. Greenbird600 macrumors member

    Jan 9, 2008
    So, I bought my mac pro about 4-5 months ago and it ran great, except for a squeaking fan. I looked through the forums for advice and every thing was basically take it to the store and get it fixed.

    Flash forward to today. I just installed a new non-apple fan to the computer. So far its working, but I'm gonna see how it preforms. Regardless, I'm going to replace the one I just put in because it is loud as hell, but if one of your front fans has a problem it does seem that you can replace the fan successfully.

    To any one considering this I impart my knowledge on the subject. You need a 120mm fan, with a Four pin connecter. Not the standard one you would see in a PC, the kind that connect to directly to the power source. I had a three pin connecter, but it worked with one pin hanging outside the connecter. My fan that was dysfunctional was my front bottom fan. I've hear that changing the rear fan requires compleat case disassembly, so to any one out that that has problems with that fan I can't help you. :(

    Well, thats all I have to say so far. If any thing changes ill post an update, I'm going install the fan controls now (SMC I think it is?) good luck to you all with similar problems.
  2. Greenbird600 thread starter macrumors member

    Jan 9, 2008
    UPDATE: well I think I found why the fan is running so loudly. SMC reports it clocking in at a steady 2000 rpm. The regular one was something like 500ish? new fan doesn't seem to work with SMC.
  3. GoCubsGo macrumors Nehalem


    Feb 19, 2005
    Well I don't know much about this but I am watching diggnation on iTunes, surfing the net, formatting an 800gb hard drive (have been for 3 hours) and using an external hard drive plugged into my airport to stream said diggnation show.
    On my menu bar it reads 81(f) and 2772 rpm. I'm guessing my fans are running at 2772?
  4. Greenbird600 thread starter macrumors member

    Jan 9, 2008
    Probably the formatting is what is driving your temps up and making the fan run faster. I replaced the older fan that squeaks until i can get a quieter one and that one according to istat is at about 800 rpm vs a 3rd party one at 2000 rpm. I wasn't able to find any fan controller that could lower it.
  5. dchao macrumors 6502a

    May 20, 2008
    Formating isn't CPU intensive, the 2700+ rpm fan speed is the CPU one, and there is no way the CPU fan need to rev that hard to do formating.

    Assuming you have not set it to 2700 rpm in SMCFanControl by mistake. I sugguest you get your MP checked by an Apple store.
  6. Gonk42 macrumors 6502

    Jan 16, 2008
    near Cambridge

    I'm not a great expert but my understanding is that four pin connectors
    go with fans with speed control, a three pin fan just goes flat out
    unless you lower the supply voltage (by sticking a resistor in the

    If I've read your post right, your fan is noisy because it is going flat
    out as the fan control can't work. You need a four pin connected fan
    such are used in CPU coolers.

    I guess there must be plenty of 120mm ones available.
  7. ghoztman macrumors regular

    May 23, 2008
    I recently bought a new MacPro and put it two new 500GB drives. A minute or two after booting up, the fans went like the clappers. So loud it was unreal. So, i kept switching the machine off.

    The I realised I needed to give it time to do it's searchlight scan. After about 30 minutes, it's calmed down and went all silent.

    My fans were also running at 2700rpm, the exhaust fan and the Front panel fan.

    When I installed apps, FCE for example, it blasted again for a few minutes, then went quiet.

    Leave it over night with nothing to do.
  8. Wayward macrumors member

    Nov 24, 2007
    That fourth pin is for Pulse Width Modulation (PWM), which is used to regulate the speed of the fan. (At least that's how it works on 4-pin CPU fans in PCs.)

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