Why is my G5 drive bay fan speeding all the time

Discussion in 'PowerPC Macs' started by SheerGold, Feb 22, 2008.

  1. SheerGold macrumors member

    Apr 20, 2006
    My G5 tower is one of the early models.

    Today I turned it on. Immediately the drive bay fan was running at maximum speed. The Mac's temperature was cold as it had not been used for 12 hours. So the speeding fan could not have been due to the drive bay being overheated.

    The fan never slows down.

    Even after a restart it immediately spins at its maximum. Plus it stays at maximum speed all the time.

    Anyone know what is causing this & how to make it work properly?
  2. lamina macrumors 68000


    Mar 9, 2006
    Shot in the dark here... turn it off, hold down the power button until you hear BOOOOOOOOOOOOOOOP and all the fans spin up to max, and release.

    Also, hold down -Opt-P-R to reset PRAM.

    Let us know.
  3. andy.barron macrumors 6502

    Nov 30, 2006
    Bedford, England
    Hi. I had the very same problem ages ago. Set the processor performance to best or fastest (sorry i'm not in front of my G5) instead of automatic.

    I believe this will sort it for you:)
  4. farrers macrumors newbie

    Jan 2, 2012
    Thank you!

    I know this forum is 4 years old, but I found it today b/c I was having this same problem. Your advice, lamina, did the trick! Thank you! Incidentally, what does holding the power button until you hear the "BOOOOOOOOOOOP" do exactly?

    Thanks again!!! :)
  5. havokalien macrumors 6502a


    Apr 27, 2006
    Kelso, Wa
    G5 fan speed

    When the pram gets corrupted or battery goes dead and resetting does not fix the issue you need the ASD for it to reset fan speed control and test hardware. Make sure to replace the battery before you do use the asd or it will forget again and fans will spin to max. Also if you have a dual processor G5 one processor maybe dead. Happens a lot, and can be checked in the ASD menu. Good luck.
  6. lamina macrumors 68000


    Mar 9, 2006
    Wow! Glad I could help. Doing that resets the power management unit, as far as I understand. Cheers!

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