Replacing worn fans on G5 DC 2.3. What exactly do I do?

Discussion in 'PowerPC Macs' started by kifkif, Jun 7, 2011.

  1. kifkif macrumors newbie

    Jun 6, 2011
    Hi again,
    I have fans with noisy bearings on my new second hand G5 Dual Core 2.3 (late 2005).
    I've read lots of threads which say "replace 'em!" and even links to websites with reams of loose fans for sale.
    But which fans do I buy?:
    I'm pretty sure the 'main' ones are the worst (the 4 around the processor I think), but if they are worn, are others in there likely to be worn too?
    What sizes? what voltages, etc?
    How do I know which ones are really going to be quiet?
    Are original apple replacements available?
    If so, are they super-quiet/worth the (undoubted) extra expense?
    And whichever ones I get:
    How do I fit them?:
    Can I find ones that will match up to the existing plastic housing/mounting, or do I need to make up mountings for them?

    I realise it's easy when you know how, but nobody seems to have managed to pass on exactly how they did it, not in a step-by-step way a fan-novice like me can follow, anyway.

    I know it can't be that difficult, but after hours of trawling through forums etc. I still haven't found any specific answers to these questions.

    I think a whole swathe of G5 owners will get down on their knees in thanks to whomever can post the definitive guide on what seems to be a very common problem!

  2. Electricidad macrumors newbie

    Jun 5, 2011
  3. Transporteur macrumors 68030

    Nov 30, 2008
    Ideally you want to buy fans with 4pin connectors, as those allow fan speed control like the original Apple ones.

    Doesn't have to be that way. To make sure which fans exactly cause the noise, just stop them using you finger. I replaced the PCIe section fan in my DC back in the days as it was by far the loudest one. I used a 4 pin BeQuiet IIRC.

    The size depends on the specific fan. Just measure the stock fans (e.g. 80x80x25mm for the PCIe fan) and buy ones that match the size. Fan sizes are standardised, so physically speaking, you can't go wrong with any fan that meets the size of the stock fan. Voltages are standardised as well. All fans can be used with up to 12V. The 4 pin fans I spoke of, are controlled (PWM in case of the Apple connector, meaning that the fan uses 12V but not constantly, which results in slower RPM, hence noise). So don't worry about voltage.

    To make sure you buy quiet fans, just read the specification and check for the db level. Less means quieter. However, keep an eye on fan's efficiency. Generally speaking, the quieter the fan, the less air it can move. Ideally, check some hardware review sites.

    Apple replacements are available and an easy fix I you're not too sure on what 3rd party fans to buy and how to install them. The thing with 3rd party fans is the connector. The pin allocation differs from the standard PC fan, so you'd have to change that. I really can't remember the right allocation, though. I used a multimeter to get it right, as there really isn't much information on the internet about this.

    And yes, expensive low noise fans are indeed worth it. They move more air than low cost fans due to an improved blade design.

    If you bought the same size, you don't have to modify anything, they snap right in. The majority of fans are fitted with rubber grommets instead of screws to reduce vibrations. Getting these out might be a bit tricky and you could end up destroying them (which I did with some of them). No biggy though, as any rubber fan grommets will fit.

    I hope that gets you going. It really isn't that complicated, just make sure you are able to disassemble the computer, get the right fans and modify their connectors. If you can find a deal on the stock Apple ones though, I'd recommend using them. High end 3rd party fans are expensive as well (although considerably more quiet than the Apple ones) and since you say you're not too familiar with this modding stuff, it might be the safer bet.
  4. kifkif thread starter macrumors newbie

    Jun 6, 2011
    Wow! Transporteur, What an absolutely awesome reply. I am not worthy!! (sound of creaking knees, and tears of relief!)
    Thank you SO much for taking the time to post your reply. I'm sure it will bring blessed relief to many others too.
  5. Transporteur macrumors 68030

    Nov 30, 2008
    You're very welcome. You might also want to take a look into this thread, which explains the standard 4 pin allocation on the fans you can buy.

    If you can find such a specification for an Apple fan (I haven't searched to be honest) you're basically done, the rest is simply swapping the fans really.
  6. Electricidad macrumors newbie

    Jun 5, 2011
    Too bad all of his post is wrong. Only the Apple fans can be used.
  7. Transporteur macrumors 68030

    Nov 30, 2008
    kifkif, just ignore this guy. He's a known troll in this forum and gets constantly banned for his hostility and spreading false information all around the forum.
    He's opened more than 10 different accounts here over the time. Once banned, he opens a new account. Quite simple to detect that it's him, though.
  8. kifkif thread starter macrumors newbie

    Jun 6, 2011
    Oh man, those trolls.. thanks for pointing it out.

    Re: your tip to stop each fan with your finger, to find the noisy one/s.
    Bingo. Just one fan is noisy - not due to wear, but because it's rotating at, or somewhere near, maximum rpm (circa 3200)!
    However, Hardware Monitor reports it as operating at minimum rpm (circa 500rpm).
    So.. I'm starting a new thread, hoping for some help with this new twist...

    That is such an awesome reply you left above. If anyone else googles in and finds it useful, please leave some appreciation on here for Transporteur!
  9. JoeG4 macrumors 68030


    Jan 11, 2002
    Bay Area, Ca.
    That fan is probably busted somehow. Several of the fans in my G5 report constant RPM rates that do not correlate to the speed the fans actually run at. It's annoying, but so far the only solution for me was to yank the (supposedly impossible to remove) blower fan at the top of my G5 and stick an 80mm antec in its place. :D The blower is just chilling out next to the video card ;)

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