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Power Mac G5 sleeps, then freezes and fans go overdrive.

I've browsed back a bit and noticed there are more than a few other people with this same issue.

I have a Power Mac G5 Dual 1.8. After upgrading to Leopard I noticed this happening more often, but ever now and then my Mac will go to sleep and freeze there. No keyboard action will wake it. Plus, while it is frozen asleep the fans to into overdrive. I have heard the fans kick up before while the machine is awake, but I have never heard anything like when this asleep/freeze happens. My wife likens it to a jet engine.

I recall this happening once through all iterations of Tiger. But with Leopard, it has now happened four times total.

I had done a clean install of Leopard, and I've only reinstalled a few other programs—iLife, iWork, Office 2004, CS 3, so no legacy from Tiger is hanging around in there.

Still, I have a habit of launching Activity Monitor when things behave strangely and I had noticed some strange things in Leopard that has me checking this out more often recently. I think I may have noticed some odd behavior by some programs that may be related to my Power Mac G5 intermittently freeze/revving unbelievably while asleep.

It seems that there is a greatest likelihood of the computer revving while asleep when the Real Memory allocated to the kernel_task process has climbed to roughly 300 MB. I thought it might also be a factor when other apps grabbed a massive chunk of Real Memory, so I've been alert for when Safari (for instance) climbs towards 300 MB of Real Memory as well. But no, the only one that seemed for certain to be related to this issue was kernel_task climbing to stratospheric Real Memory amounts.

Quiting apps helps get stupid programs like Safari to free up its Real Memory allocation, but I don't know of any way to get kernel_task to release its Real Memory allocation to proper levels besides restarting the entire computer.

Ever since I have noticed this apparent correlation between kernal_task and the freeze/sleep + fans issue, I restart or shutdown my Mac. And since I began shutting down my Mac when I see the Real Memory of kernel_task getting too high I have not had my Power Mac experience the freeze/sleep + fans.

I would be curious if anyone else who had noticed this freeze/sleep + fans issue has noticed if doing what I describe above helps them. I'm not sure why roughly 300MB of Real Memory seems to be a tipping point for me and I wonder if it might be a different amount for other people with Power Mac G5s and this issue. I wonder why kernel_task climbs to the heavens like a spreading wildfire grabbing more Real Memory and I wonder why Safari does it as well.

Dual 1.8 GHz G5, Mac OS X (10.5.1)

Posted on Dec 7, 2007 9:17 PM

Reply
99 replies

Aug 19, 2008 11:05 AM in response to Anondson

Hi all,

Well, my problem with my 2.5 Quad still persists. The fans come whirring on at olympic speed and the only cure seems to pull the plug.

I finally took it to my local Apple store for them to give it a look over in the Genius Bar. Would you believe that when it was there it behaved faultlessly...???...!!! We started it up, ran apps and it went to sleep without the fans going into 'turbo mode' once

It is now with them for a full diagnostic check to try and re create the problems I'm having. This high speed fan sleep problem has only occurred since I 'upgraded to Leopard'. Never had a problem with earlier versions of OSX.

The chap at the Apple store was pointing fingers to one of my peripherals and said that could be the problem? All I have connected are the following:

Apple Cinema 23" Display (old G4 style plastic case) via DVI to ADC Adaptor.
Apple Studio 17" Display (old G4 style case) via DVI to ADC Adaptor.
Wacom Intuos 2 Drawing Tablet.
Canon Lide 30 Scanner.
Lacie D2 200GB Exxternal HD via Firewire.
Harmon Kardon Soundsticks.

Does anyone think these items could be the cause? I have tried the G5 with just the screens connected and the turbo fan problem happens again.

Anyway, the Mac is at the Apple Store and I'm just hoping that they find the problem. I'm so pleased now that I bought the extended warranty at the time of purchase. Expires in Nov 08 so at least I have a few months of peace of mind.

Will report back with progress.

YZ

Aug 19, 2008 12:12 PM in response to Anondson

Thanks Daniella and Cameraflyer.

I'll definitely be downloading the D2 update. Many thanks for the link, much appreciated.

I thought that the old style screens were pretty much out of the equation but you never know, that's why I thought I'd list them anyway just in case there may be an issue? I don't really want to give them up for the new style screens as I like them so much, designs classics for sure IMHO 😉

I guess I'll just have to wait a few days and see what Apple have to say.

YZ

Sep 26, 2008 4:33 PM in response to Cameraflyer

I am having the same problems with my Dual 2gig G5. The machine has performed flawlessly since Summer of 2004. It started in August when I added more RAM to run AVID. I believe there was an update about the same time. I took the new RAM out. No change.

I'm running a Seri-Tec1S2 PCI SATA card in Slot 4 and a Blackmagic HD video card. Again, this computer has done a tremendous amount of HD editing with absolutely no problems. Suddenly the freeze/fan problem. The computer is just sitting idle.

Sep 30, 2008 5:38 PM in response to Denbee

Apple ended up replacing my computer with a new MacPro last July after I posted. They checked the RAM and whatever else they could think of, but didn't want to start replacing parts when they were not even sure if it would solve the problems. I was lucky that I still had 6 months left on my Applecare with that machine. I am out of the power pc's now except for my 5 year old laptop.

Oct 17, 2008 8:36 AM in response to Anondson

So, an update. At this time my computer is running. Has been for a few months now since I can't let it go to sleep. Seems everything is fine so long as I don't let it sleep and all the other issues have gone away. The last time it crashed and I could not get it started I tried a lot of different things to isolate the problem and get it running. Ran it with & without various ram chips, on one processor only, then the other... at times it would at least get it started, eventually, but then would still crash, freeze, do the fan thing or something. Then it crashed and absolutely nothing I did would get it started again. I finally started getting a little abusive, as oddly enough this is when it would startup for me. Even though there was no firmware update available for it, I pressed and held the power button till I heard the tone (this is how a firmware update used to be done) then let it start (may have done a PRAM zap immediately following, can't remember) and everything has been fine since. All except I'm afraid to let it sleep (really killing me) or shut it down or restart it, which also means I can't update it. It's like trying to decide when I think I can be without one of my legs for the next month or so... if it doesn't start.

I've been running on 10.5.4 for a while now but would like to do the software update to 10.5.5. Has anyone noticed if this update has changed anything for this problem? I would really love to let my machine sleep again. or at least be able to shut it down or restart it once in a while.

Power Mac G5 sleeps, then freezes and fans go overdrive.

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