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PMG5 fan(s?) acting up… Scared! What's the drill?

530 Views 12 Replies Latest reply: Apr 27, 2011 12:46 PM by Nina R RSS
Nina R Level 1 Level 1 (10 points)
Currently Being Moderated
Apr 25, 2011 7:47 AM

My normally whisper-quiet PM G5 revved its fan(s?) a bit on first start-up today. I haven't heard fan noise since the last time it pitched a diva fit, at least a year ago. My stomach turned.


I shut down, wiped some dust off the front grill with my hand, restarted. Turned on my external drive, which the G5 couldn't mount the first time for whatever reason but did when told "back up now." Completed backup. Fan noise came and went. It sometimes makes that sickening up/down sound.


Reset my SpiralBound Pro app not to launch at login. I had set it to do that about 3 days ago, with some trepidation. It seems that every time I set any app to launch at startup, I soon begin having trouble with this machine. Restarted. Still have fan noise. Fairly low volume, steady now. Man, do I hate this sound. It has always been associated with serious problems throughout the almost 6 years I've had the machine.


I'm going to shut down, disconnect AC from the rear for a few minutes, check my manual, look inside and see if I see any gross dust problems or cockroaches (possible—I know, ugh) in there, then power on again.


Meanwhile, can someone give me bullet points on what diagnostics I should be doing?


Am I correct in thinking this is unlikely to have anything to do with the hard drive?


In the last few minutes, it has quieted down to the normal almost inaudible level three times, but then revved again gently for a few minutes. Quiet now. I wonder if it is working its way out of something…


I'm long term unemployed, can't afford to have my old friend die right now. Thanks…



Power Mac G5 2.0 (late '05), two PM 7600s (bless 'em), beige G3, CDMA iPhone 4, Mac OS X (10.5.8)
  • BDAqua Level 10 Level 10 (114,715 points)

    Hi Nina,


    Be sure to blow out the dust from the interior,

    Get Temperature Monitor to see if it's heat related...



    And/or iStat Pro...



    If you have any temps in the 70°C/160°F range, that's likely it.


    >Am I correct in thinking this is unlikely to have anything to do with the hard drive?


    Not the likeliest suspect at the moment.

  • old comm guy Level 4 Level 4 (2,230 points)

    To add to BD's comments, is your machine liquid cooled?  In your case, I think that would only be the Quad 2.5.  See what temp monitor or iStat report for sure, as that is the first indication of problems.  If the CPU die temps are high and you have the quad, then you need to examine for coolant issues.  Let's hope that isn't the case.

  • WAM2 Calculating status...

    My powermac g5 has just started doing this something today, I have fixed mine by shutting off the mac, opening the side of the case and pressing the PMU reset button on the logic board... Though if you are on a quad  then this May not fix the problem and your liquid coolant system may be getting old ( and failing) causing the fans to take over and since it is. Quad the fans are going to be loud because of the liquid cooling system failing. I have the dual 2ghz and still love it, though I just replaced it with a new iMac. Try pressing that PMU button and see if that helps, and if your on a quad look for leaks.. Hope I helped.


    Typed on an iPad 2.

  • old comm guy Level 4 Level 4 (2,230 points)

    Nina R wrote:


    P.S. It's a dual core 2.0, I'm 99% certain it is not liquid cooled.


    As am I.  See what temperature monitor is saying.  Especially look at the history window.  You will need to assign different colors to different sensors (makes it kind of artistic, in a way) but you will be able to see what is going on and what, if anything is rising in temperature.


    Also, another thing you can use is Activity Monitor and just keep the CPU Usage monitor running in the corner of your display.  That will tell you if a CPU is getting overly busy and you can track that down by looking at the full A-M display and sorting on CPU usage.

  • Appaloosa mac man Level 5 Level 5 (4,300 points)



    Compressed air has a second side effect.  Too much velocity creates static electricity.  A gentle vacuum is much better around electronics.


    As for the fan.  Our G5 cycles up and down a lot and it is not a sign of impending CPU failure.  Take a look at 'Activity Monitor' to see if some application is ramping up in the background and causing the fans to anticipate the need to cool.  Activity Monitor is found in the Utilities folder of the Applications folder.


    Hope that helps.




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