G5 Fans Suddenly Speed Up & Get Loud?!?!

Discussion in 'Macintosh Computers' started by Skaught, Oct 14, 2003.

  1. Skaught macrumors member

    Jun 12, 2003
    My G5 was asleep the other day. I hit the space bar to wake it up, but it didn't work. I tapped a couple more times, and nothing. Then suddenly the fans start speeding up and getting loud. I mean LOUD. Nothing like when it's working properly. More like it was trying to fly away. It was scary! I couldn't shut it down so I had to pull the power cord. It restarted fine, thankfully, but now I'm worried. What was that all about???

  2. yamabushi macrumors 65816


    Oct 6, 2003
    Were you running any applications while it slept? The fans speeding up generally means that the processor was working hard.
  3. Catfish_Man macrumors 68030


    Sep 13, 2001
    Portland, OR
    If it had a kernel panic trying to wake from sleep, it might disable the fan control program (similar to when it's in FireWire target disk mode).
  4. Skaught thread starter macrumors member

    Jun 12, 2003
    No, this wasn't any normal fan activity, like when an application is crunching hard. This was "OMIGOD IT'S GOING TO EXPLODE" loud. This was hurricane force speeds, "what did you say I can't hear you over these fans" loud.

  5. coolbreeze macrumors 68000


    Jan 20, 2003
    Well, I don't have a G5....or a G4 for that matter. But I did try the hardware test CD that came with my iBook today. While the test was running (specifically the memory test), my fan kicked on. No big deal, as loud as it usually is when it's on. Then it whirred up to an extremely high RPM for about 30 seconds. I'm talking LOUD. I was honestly thinking my iBook was going to take off or something.:eek: It really was very loud!! I can't imagine the G5's fans at full blast.

    I also have problems waking from sleep...but not the fan-related issue you mention. Hopefully Apple will work out the sleep-->wake bugs in Panther.
  6. Santiago macrumors regular

    Jun 14, 2002
    Mountain View, California
    By default, every fan in the G5 runs at full blast, producing an accurate simulation of a jet engine, but keeping anything from overheating. When Mac OS X is running correctly, it dynamically adjusts the fan speeds to provide just enough cooling. If the OS goes down, the fans go to max as a safety feature. If you run an OS that doesn't know how to manage the fans, like Linux, then you'll have constant jet-engine mode.
  7. Makosuke macrumors 603

    Aug 15, 2001
    The Cool Part of CA, USA
    My G5 isn't here yet, but it sounds a whole lot like your machine panicked or otherwise crashed on wake from sleep. That caused the OS fan control process to die, and as a result whatever chip the computer uses to do fan control went into the same emergency full-blast mode it uses when you boot the thing in firewire disk mode, with an unsupported OS, or try to run it with the side panel open.

    As loud as it is, it shouldn't be anything to worry about. You also didn't have to pull the power cord--unless Apple's changed things a lot, which I doubt, holding in the power button for five seconds should do a forced power down, which is a bit more gentle than yanking the cord.

    Enjoy your beast, and may it never panic again.
  8. colinet macrumors 6502

    Sep 5, 2003
    My dual G5 just did exactly the same thing. I ended up turning it off at the mains and re-starting which it did no problem except it did so twice - startup noise/ grey screen/ black screen / startup screen then blue screen and OK.

    Not sure what makes it happen but I've woken the machine up from sleep lots of other times without it happening - must be a little software bug I reckon, but nothing serious.

    Who know 10.3 which we'l hjave seen might sort it.
  9. Frohickey macrumors 6502a

    Feb 27, 2003
    Its 'normal' for the fans to be at full speed. This is what prevents the G5 from being damaged. Lets say the machine somehow crashed real bad, but the fans are on very low, you could end up with a really dead system with damaged components from heat if the fans were low.

    So, instead of 'low speed' as the normal state, the normal state is 'high speed', as in high speed fans. And you have the OS continually talk to whatever is controlling the fans to slow them down to just enough for cooling and not any more than that.

    Think of it as a safety mechanism.
  10. Rezet macrumors 6502a


    Apr 21, 2003
    Connecticut, United States of America
    Don't worry dude... I have a G5 also and fan speed up after sleep is normal. It pushes out the the hot air out of the case. I dont think they should do it too fast, so in yoru case it probably was nothing more than some glitch in programs that were running that somehow didnt like os. Im pretty sure it wont happen again.

    BTW, when fans got loud, did red light lit up inside the case also?
  11. IainB macrumors newbie


    Nov 26, 2003
    Definitely an unscripted feature. I have been transferring files from old G4 to new G5 in firewire target mode and was alarmed by the gradual rev up of all (?) fans to full blast. It's like standing at the end of a runway. I assumed something was terribly wrong and the whole thing would have to go back.

    Only web research reveals it's typical in this mode.

    In normal operation it's a lot quieter than G4/450. The only other time I've heard the fans is when you wake it from sleep and it does a little "revvv...whooshh" act which is so organic I can't believe it wasn't carefully sound-designed.

    Might be worth taking the side off and reseating the removable fan unit to make sure all the connections are okay.
  12. wibbler macrumors newbie

    Feb 11, 2004
    G5 overdrive

    My 1.6 G5 is also doing the big fan trip.

    This ONLY happens during sleep mode, so I doubt the machine is trying to keep cool because it is being worked hard. Besides, even when it IS worked hard (running sewveral active apps, copying to a FW disk, burning iTunes playlists while also importing iTunes etc etc) it DOESN'T get ANYTHING like as LOUD.

    I leave my G5 running 24/7 even when I am away (so I can do remote logins) - now I am very worried about doing this as I have visions of my G5 playing Concorde for three weeks! Argh!

    So any idea if there is a fix?

    Apple? Anybody?
  13. Mav451 macrumors 68000


    Jul 1, 2003
    If the fan control is in the OS, than perhaps a simple update will deal with it...but i have a feeling this is also something on the motherboard.

    My (old) nForce2 board has a feature called "Q-Fan": (http://usa.asus.com/mb/qfan.htm)

    Perhaps a bios fix (or Mac-equivalent) will deal with this as well? Q-Fan originally didn't work well in early BIOS revisions, but was later fixed.
  14. teetoo macrumors member

    Feb 5, 2002
    Had the same experience this morning as I started a G5 up in the studio. I was on the phone, stereo on in the background and this noise just got louder and louder behind me - I could hear it above everything, it is pretty scary, at the time I tried to shut it down using the startup button with no joy, I then resorted to scrambling around under the desking trying to find the damm plug for the mac in the usual spagetti mess of cables and wires half expecting the whole thing to blow-up in my face at any time.

    Nice start to the day.
  15. wibbler macrumors newbie

    Feb 11, 2004
    fan firmware

    There is a firmware update for the G5 fans on the apple support area. But I CANT get it to load at all. I've followed the instructions but when the mac boots into the Firmware, there is absolutely no action from the firware updater, nada, zilch, it isn't even there.

    My System Profile shows :

    Boot ROM Version: 5.01f1

    So I'm guessing that means my FW version is 5.01 - am I right?

    The updater is V 5.1.4

    HELP!?! I REALLY don't want to spend hours hangin' on the telephone (I'm not blonde) to Apple Support - I'd rather sort this out here, the easy way

  16. lem0nayde macrumors regular

    Apr 26, 2002
    I've had this same thing happen too. I wouldn't worry about it. As others have said, it is just the hardware reaction to software failure. It happens to me whenever I try and run the Hardware Test from the DVD and the program crashes or takes too long. In fact, I've yet to run that program all the way through successfully...it always crashes.

    The G5 needs a lot of work - it was clearly rushed to market and the design and function were not thought out thoroughly. My first one was a dud and had to be sent back. The replacement runs fine - but I had to manually move the heat sensor behind the drives, because it was not placed in an area that truly read the heat of the drives - hence making the drives burn up and destroy some of my data.

    I am annoyed with Apple for suckering me a bit with this hardware. It's fine though, it runs fast as hell most the time - but people who had the luxury to wait until the RevBs will be glad they did.

    I wish Apple would offer a trade-up program for consumers when the next revision comes out. I'd be signed up in a heartbeat.

  17. Mav451 macrumors 68000


    Jul 1, 2003
    lem0nayde - you mean a program similar to the ones car dealerships run with their customers?

    I know my parents always receive ones about the Toyota (trade in old, get xxxx amount off the 2004 model). It's not a bad idea since the traded in one will get inspected and resold as used --- which is much more affordable for those looking for used. Then you can get the new one for quite a bit less. Everyone wins. I'm sure people out there wouldn't mind getting a used (but inspected/verified) 2.0G5 or even the old single 1.8 systems for much less, based on trading in their G4s.

    Then the G4, especially the old PMacs, can go to those who want power (not iMacs) and they can GET that by trading in they even older G3 iBooks...ad infinitum.

    It'd be a good idea, considering Apple is like the Lexus/Toyota of the computer world.
  18. lem0nayde macrumors regular

    Apr 26, 2002
    Hahah. Good analogy. Precisely what I meant, although maybe not as far back as the G3.

    I think Apple should quietly acknowledge that they f'ed up the original G5s and should give their customers a chance to upgrade. You know, since we were kind enough to be their guinea pigs.

    A boy can dream, can't he?

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