CPU fan replacement G4 Digital Audio.

Discussion in 'PowerPC Macs' started by SomeSwede, Feb 26, 2009.

  1. macrumors member

    Joined:
    Feb 26, 2009
    Location:
    Land of ice and snow.
    #1
    Hi. I got an old G4 Digital Audio as home server / seedbox, and recently i got fed up with the horrible noise and as a first step i replaced the 120 mm fan with a new and quiet one, and it is working perfectly. However, when i replaced it i noticed that the CPU fan is now the loudest, and a computer that is on 24/7 can never be too quiet.

    Can i replace the CPU fan with any fan of the right size?

    Are there any requirements regarding fan speed/air throughput?

    Do i have to connect the fan to the non-standard two pin connection where the original fan was connected or can i just use a normal 3 to 4 converter and connect it to the spare 4 pin power outlet?
     
  2. macrumors 6502

    AlexMaximus

    Joined:
    Aug 15, 2006
    Location:
    Boondocks
    #2
    Fan Specialist ...

    Hi there,

    I did some extensive cooling and noise reduction projects on my G4 MDD a while back.
    At the bottom line, you want to make sure to have a similar or better airflow on the CPU's heat sink with less noise. Usually you can do that by doubling the fan number in you G4 but using lower spinning fans which are a lot less noisy. However today's fans have improved a lot so you may not even need to go that route.
    From my experience the best fans on the noise/airflow ratio are the SilenX fans. To get an idea, check out this page her:

    http://www.pc-cooling.at/advanced_s...lude_set=1&page=1&manufacturers_id=80&cPath=2

    Make sure to check out how much airflow your current fan shovels through.

    On the fan connector - Since I really don't know which connector do you have, its hard to tell. I really never used more then the simple two wires (red&black). If you are skilled you can simply change the connectors as you want since you can even buy those connectors separate.
    Regarding noise, there is also the option to use some cables where you can run a fan on a reduced voltage level to spin slower and less noisy. However this reduces the the airflow as well.

    Good luck !
     
  3. macrumors 6502

    AlexMaximus

    Joined:
    Aug 15, 2006
    Location:
    Boondocks
    #3
    Fan Specialist ...

    Hi there,

    I did some extensive cooling and noise reduction projects on my G4 MDD a while back.
    At the bottom line, you want to make sure to have a similar or better airflow on the CPU's heat sink with less noise. Usually you can do that by doubling the fan number in you G4 but using lower spinning fans which are a lot less noisy. However today's fans have improved a lot so you may not even need to go that route.
    From my experience the best fans on the noise/airflow ratio are the SilenX fans. To get an idea, check out this page her:

    http://www.pc-cooling.at/advanced_s...lude_set=1&page=1&manufacturers_id=80&cPath=2

    Make sure to check out how much airflow your current fan shovels through.

    On the fan connector - Since I really don't know which connector do you have, its hard to tell. I really never used more then the simple two wires (red&black). If you are skilled you can simply change the connectors as you want since you can even buy those connectors separate.
    Regarding noise, there is also the option to use some cables where you can run a fan on a reduced voltage level to spin slower and less noisy. However this reduces the the airflow as well.

    Good luck !
     
  4. thread starter macrumors member

    Joined:
    Feb 26, 2009
    Location:
    Land of ice and snow.
    #4
    Thank you. I will see if i can get one from a nearby retailer.

    I will try.

    I wasn't aware that i could buy the connector separate, since the local PC dealer claimed to never before have seen the kind of connector the old 120 mm fan used.

    Thanks for the help.
     
  5. thread starter macrumors member

    Joined:
    Feb 26, 2009
    Location:
    Land of ice and snow.
    #5
    I have now replaced the fan with a new quieter fan with better airflow and so far the computer is running without problems.
    As i suspected the two pin connection used by Apple was yet another of their silly ideas, not used by anyone else. However i connected the fan to a standard four pin molex connector using a 3 to 4 adapter.

    One more question. Should the CPU blow hot air away from the processor out of the case, our should it suck in cold air?
     
  6. macrumors 68000

    Joined:
    Jan 17, 2008
    Location:
    Philly
    #6
    I like getting cold air in. Hot air sees itself out.
     
  7. macrumors 6502

    AlexMaximus

    Joined:
    Aug 15, 2006
    Location:
    Boondocks
    #7
    If I recall correctly, the 120 mm case fan blows the air out of the case. Since the CPU sits close to it, the fan supposed to blow over the metal heat sink to collect the heat energy and then gets blown out through the 120 mm fan. If that is correct its would be to blow, not to suck...

    Check your new fan, sometimes there are little black arrows on the outside fan cage to indicate the airflow and turning direction of the fan wheel. Its usually on one of the four outsides stamped on the black plastic cage.
    Then compare it with the installation of your original fan to be sure...

    :eek:
     
  8. macrumors 601

    OrangeSVTguy

    Joined:
    Sep 16, 2007
    Location:
    Northeastern Ohio
    #8
    Yes the main 120mm blows the air out. The air comes out the bottom of the case. Don't know why they did that as it seems like the opening isn't even large enough to disperse all that air. I put a bottle cap in the bottom to make the opening bigger. I know that I took that side panel off and cut out that whole "screened" area as that builds up with dust creating even more of a restriction.

    I've also cut in a 60mm fan in the bottom to draw more cool air in. For a machine that will run 24/7, you want the best possible air circulation with minimal restriction.

    [​IMG][​IMG][​IMG]
    [​IMG][​IMG][​IMG]
     
  9. macrumors 6502

    Dave H

    Joined:
    Mar 2, 2008
    Location:
    California
    #9
    I'm not sure exactly when Apple changed it, but in my Digital Audio (which was built as a dual 533) the original 120mm case fan was for intake.
    I had thought the Quicksilver was the first model to have the 120mm fan as exhaust.
     
  10. thread starter macrumors member

    Joined:
    Feb 26, 2009
    Location:
    Land of ice and snow.
    #10
    Thank you all for the help. :)

    My G4 has been running fine for a few days by now. Everything appears to be working correctly, and the annoying vacuum cleaner sound is gone. It is still audible, but since the Mac lives in my wardrobe it is no big deal.

    Haha, yeah, next time i will remember to check it before i remove the original fan. :D
     
  11. macrumors newbie

    Joined:
    May 12, 2009
    #11
    Hi SomeSwede. Did you have any problems replacing the 120mm fan, was the connection standard? I have a G4 (Digital Audio) that I've owned from new (2001). The fans have always been noisy but this week the larger case fan has become even noisier and now sound like a vacuum cleaner. Apart from this the machine is operating fine so I don't want to trash it. I'd like to replace the fan in the CPU too but that sounds more complicated. Was it? Did you have to do any soldering? Where did you buy your fans, I live out in the sticks in the UK so I'd order online? I'd appreciate any advice you can offer. Thanks.
     
  12. thread starter macrumors member

    Joined:
    Feb 26, 2009
    Location:
    Land of ice and snow.
    #12
    Really sorry about the late reply, i have not visited the forum for some time.

    Both the 120 mm fan and the smaller CPU fan had originally a non-standard 2-pin connector (typical Apple fashion i guess). The fans i used as replacements had normal three pin molex connectors, which i connected to a spare connector from the power supply using two adapters of this model: http://www.dtekcustoms.com/ProductImages/products/addons/3-4 pin.jpg

    It was really easy and all i needed was a set of screwdrivers. I bought the fans from a local PC dealer. Just make sure the cable is long enough to reach the connector by the power supply even when the lid is open. The G4 has been on 24/7 for almost three months by now without any problems.

    You can use this service manual for guidance: http://data.fuskbugg.se/skalman01/Apple_PowerMac_G4.pdf
     
  13. macrumors newbie

    Joined:
    May 12, 2009
    #13
    Thanks for your reply but I gave up hope of receiving one and have not checked the forum until now. I am so please you did reply but I would still like your help if you are around.

    Did you have any problems opening the power supply to replace the fan? How easy was that? I've been warned it is very dangerous because, "Lethal voltages can be stored in a PSU for weeks after it has been disconnected from the mains and if you touch the wrong thing, it could kill you". I presume you survived so I'm curious to know your method of operation.

    Many thanks ;)
     
  14. macrumors 6502

    Dave H

    Joined:
    Mar 2, 2008
    Location:
    California
    #14
    If it helps, I used this page for a general reference before I replaced the PSU fan in my Digital Audio.
     
  15. macrumors newbie

    Joined:
    Feb 20, 2010
    #15
    g4 cooling

    Here's a dumb idea!
    What I've done for years is to solder a 56 ohm resister to all the original fans, all the conectors work. I know I am cutting the noise in half and cfs too. If the fan is still noisy, I replace it [SilentX are good]. I do this to all 3 fans. The power supply fan is a little harder to get to, but I doubt the capacitors could kill you – just unplug it and wait till tomorrow – frankly I never wait and I’ve done this a dozen times. Cutting out all the metal grids against a fan is also worth it; I use metal snips, not too pretty but transparent, keep the wires out of the 120cm.
    Fan direction - oh boy!
    Anything that sucks air off the floor and sends it out the psu is going to get dirty quick at least in this house. On-the-other-hand, if the psu is at the top of the box, it makes no sense to try to send the hot air into more hot air and out the bottom. PMs have the psu at the top. 2 fans blowing or sucking are noisier than a push pull situation and move less air. So I tape the vents at the bottom, force air in to the processor [some of these fans are too noisy and have to be replaced and others aren’t], blow air out thru the psu, and the big one sucks air into the box 4 to 6 inches off the floor and out where it can, mostly the psu and creates a positive pressure in the box.
    If I fry the box, well whose fault is that, I’ll fix it or toss it – but I listen to music not the boxes. I have screwed up here and there, but I am running boxes 4 or 5 years with no noise and no problems. The g4 are the loudest but still near silent.
    Also makes sense to sleep your boxes and never turn them off for more than a few minutes; you don’t want the temps to change quickly and boxes are happy warm to hot, and stable.
     
  16. macrumors newbie

    Joined:
    May 12, 2009
    #16
    Just to let you know I’ve replaced the fan in the PSU and I’m alive to tell the tale! For quietness and efficiency I was advised to buy a Coolink SWIF 1500 RPM to replace the PSU fan and a Scythe S-flex 800 rpm to replace the 120mm main case fan. Both fans are now fitted, running and my Mac is back working.

    The fans are definitely quieter but my expectations were perhaps too high. I was hoping for almost silence but there is an audible whirring hum. I can only blame natural acoustics I suppose; the, albeit small, sounds created by the fans as well as other components are carried and amplified by the inner metal box frame. The PSU is a metal case mounted on a metal frame within the outer plastic case; the bigger fan is mounted against the side of the inner metal frame. There is probably also a hum from the hard drives, also mounted on the metal frame, which adds to the whole.

    Thanks to all for your advice.
     

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