Powermac G5 SP 1.8 roaring fans

Discussion in 'PowerPC Macs' started by ec-designs, Oct 26, 2006.

  1. ec-designs macrumors newbie

    Oct 26, 2006
    Hi all, I am new to this forum.

    I have a strange problem with the powermac G5 1.8 SP, yes the one with the hardware bug. It was my first mac, what a dissapointment. The bug was partly solved with the firmware upgrade, but after that it still behaved strangely. The fans suddenly go up to maximum speed every hour, then quikcly return to normal. There still have been lockup's / beachballing with USB, and overall slow performance.

    Now I am running the latest mac osx Tiger version, about a few weeks ago, the fans start revving up almost to maximum, all the time, regardless of cpu load. The cpu temperature reads about 60...65 degrees centigrade when idling (minimum cpu load), cpu setting is already on "reduced speed". After switching-on, cpu temperature is already 60 degrees centigrade. The cpu heatsink is stonecold, as is the exhaust airflow. The cpu 2 fans roar like mad and keep revving up and down. When I remove the plastic transparent cover, the photocell is activated and a red LED comes on, now the fans immediately return to normal speed.

    Anybody else had similar problems wit the powermac G5 SP 1.8Ghz ?
  2. MacBoobsPro macrumors 603


    Jan 10, 2006
    If i remember a workaround was to set the processor to highest performance. The fans should quiten down after that. Maybe that has changed since the latest firmware but give it a try nonetheless.

    Hope it works. That would bug the *naughty word* out of me.
  3. skunk macrumors G4


    Jun 29, 2002
    Republic of Ukistan
  4. ec-designs thread starter macrumors newbie

    Oct 26, 2006
    fan problem osx update related?

    Hi stuartluff,

    Thans for your reply [post #2],

    Sorry, I have tried all possible settings already, including automatic and maximum, nothing helps. The fans start revving up immediately after booting. Even when idling the fans keep running at a very high speed and make a hell of a noise. The problems started after one of the latest mac osx updates. I also tried resetting PRAM (alt+option+p+r) and disconnecting the powermac from the mains for a day. There is no processor intensive program running. Seems there is a relation to one of the latest mac osx updates.

    Another problem is that the fan speed on all new mac's is increased / decreased in steps, this is very annoying as it's much easier to get used to a constant fan noise or a fan that very gradually changes speed.
  5. MacBoobsPro macrumors 603


    Jan 10, 2006
    Mine Rev loud on start-up. Its part of the start-up process (i think) lasts about 2 seconds. Are you sure you have the latest firmware? I recall seeing a relatively new one. I thought it was for my Rev a 1.8DP so downloaded it. Only to find it was for the single CPU 1.8 G5. It was on Apple.com under software downloads. I cant remember if Firmware updates show up in Software update?

    SKUNK - Thats was what I was thinking of. But its too 'naughty' to be said out loud. My mom would zuning kill me... DOH!!!
  6. glennp macrumors member

    Aug 7, 2006
    Washington, DC
    Could be. I've experienced increased fan activity after an upgrade that disappeared after the next .x update. Try reapplying the latest combo update package. It couldn't hurt.
  7. Redboy macrumors member

    Jul 19, 2003
    Sorry, I have a SP 1.8 and I haven't had any problems for probably 6 or 8 months. For a long time it just wouldn't wake from sleep. The fan activity is higher than it was int eh past, but I almost never have the airplane noise unless it has totally locked up (once in a while happens on startup, I think related to a Firewire HD).
  8. ec-designs thread starter macrumors newbie

    Oct 26, 2006
    Hi stuartluff,

    Thanks for your reply [post #5]

    My G5 cpu fans rev to almost maximum directly after boot and remain at that high speed for hours on end, even when booting from the mac installation CD, the fans remain roaring.

    I just did a complete new install from the original CD's, on a blank HD, problem persists, so it's not caused by a damaged operating system.

    Reported cpu temperature keeps increasing gradually, it's now idling at 70 degrees centigrade, the cpu heatsink is still cold to the touch, and the exhaust air is cold as well. Very strange.

    I already installed the firmware upgrade, re-installing is not allowed
  9. MacBoobsPro macrumors 603


    Jan 10, 2006
    I know its a daft question but I have to ask, you do have the clear plastic thing and cover in place when the mac is on don't you?

    If not the fans will be crazy whatever you do. If you do have them in place and you are still having problems a call to Apple may be the only course of action if you have already reset the PMU and reinstalled OSX.
  10. MRU Suspended


    Aug 23, 2005
    I had a similar problem last year with my PMg5 1.8 dual. It was just the start of a logic board failure :eek:
  11. ec-designs thread starter macrumors newbie

    Oct 26, 2006
    Hi stuartluff,

    Thanks for your reply [post #9]

    Of course I have the clear plastic part and the aluminum cover in place during normal operation. Since the processor seems to overheat while the heatsink remains cool, I am beginning to suspect the coolant has evaporated from the heatpipe over time. Due to inefficient cooling the fans keep ramping up. The fact that this problem started to occur after the latest osx updates must have been a coincidence.

    The powermac also emitted a strong chemical smell from the day I bought it, perhaps this was caused by the slowly evaporating coolant. Now this smell is almost gone.....
  12. stoked1 macrumors newbie

    Jun 29, 2009
    My PM G5 2.0 dual has the roaring fan (I like the "Airplane" description) disease where it will switch the grey screens off during boot up and sit there displaying nothing for hours while the fans steadily work themselves up into an inferno.

    I've done the repair permissions, repair disc using the system DVD, but no avail.
    I've just tried reinstalling from the system DVD, using Archive Installation, but when I came in after leaving it going for an hour, screens were dark, computer locked up and fans going like an F18.

    "Zune!" I said, trying to maintain self-control... (thanks for the new word, Skunk)

    I'm hoping it's not my system board...
  13. gugucom macrumors 68020


    May 21, 2009
    Munich, Germany
    G5s need CPU recalibration after CPU changes. It has been known that G5 PM CPU had intermittent boot failures and finally ended up with the aircraft situation. Calibration (done by AASPs) might help and if I had such a machine I would investigate the heat transfer between CPU and heat sink. Sometimes the CPU daughter board isn't fitted very well to the heat sink or the thermal grease failed.

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