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Level 1

9 points

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

99 replies

Jan 27, 2008 12:30 PM in response to Anondson

Same problem(s) here. Did archive & install, tried everything I can think of such as trashing prefs, hardware tests, reset PMU, etc. Nothing has solved this problem. Won't wake from sleep 95% of the time. Hangs on boot most times. Spinning wheel often from kernal_task. Safari & Firefox hogging memory and needing to quit them often. Roaring fans when wake from sleep. Only the sleep problems carried over from Tiger. I could work for a few hours in Tiger before the memory useage would climb to 1 GB. With Leopard memory useage often approaches 1 GB very soon after boot. I regularly run permissions, disk warrior, techtools, cocktail, etc. Temperature Monitor shows everything fine. I would do a clean install if I thought that would help, but others have tried that without success.

Power Mac G5 dual 2 GHz (1st generation)
OS X 10.5.1
Memory: 1.5 GB
ATI Radeon 9600 Pro

foertter

Level 1

0 points

Jan 27, 2008 1:36 PM in response to Anondson

If I press the little tiny button on the logic board it restarts.

it's become so annoying because I can no longer just reboot.

Mar 3, 2008 12:38 PM in response to Anondson

I've having the same issue on a dual 2.0 G5. It first happened under 10.4 about 6 months ago and I didn't think much of it, but since then either waking from sleep or occasionally on startup the machine freezes and/or kernel panics and the fans go into over drive on a far more regular basis. I did upgrade to 10.5 a few months ago and the although the frequency of the issue increased, it's unclear if 10.5 is a factor. I can't recall if there was a firmware or other update installed that corresponded to the issue, but my biggest concern is the increase in frequency.

My AppleCare expired in November so I've been hesitant to take it in, but sounds like numerous people are having the issue so hopefully a fix is imminent.

adsfushi72

Level 4

1,115 points

Mar 31, 2008 8:41 AM in response to Anondson

I, too, have come back to my Mac to find the fans roaring. It seemed to happen randomly. Then, I found that I could produce the problem by putting the computer to sleep with option-apple-eject when there was a lot of drive activity. Since I usually put the computer to sleep using that shortcut, I think that that may explain my problem.
Does anyone else put the computer to sleep with that shortcut? If so, try using the normal way (Apple menu-sleep) instead.

bustout

Level 1

25 points

Mar 31, 2008 8:52 AM in response to adsfushi72

Used to have the same problem in the last few years, till today, now I can't get mine back, my thread:
http://discussions.apple.com/message.jspa?messageID=6947921#6947921

foertter

Level 1

0 points

Mar 31, 2008 9:38 AM in response to bustout

the only "fix" is to press the teeny button on the logic board. I think it's the PMU and I guess it would make sense since the fans roar.

bustout

Level 1

25 points

Mar 31, 2008 9:59 AM in response to foertter

Press the button on boot or??

adsfushi72

Level 4

1,115 points

Mar 31, 2008 10:26 AM in response to Anondson

Never mind. I just put the computer to sleep the normal way and had the same problem. But I have an idea:
If the problem happens when there's disk activity as the computer goes to sleep, then setting hard-disk sleep to happen before normal sleep should solve it. Since there's no way to set that in System Preferences, you will have to use the pmset command in Terminal.
The syntax is:
pmset -a disksleep n
to spin down the hard disk after n minutes.

adsfushi72

Level 4

1,115 points

Mar 31, 2008 10:54 AM in response to adsfushi72

I forgot something. You have to run pmset as root to change anything, so when you enter that command in Terminal, put the word "sudo" at the beginning. You'll have to authenticate as an administrator.

adsfushi72

Level 4

1,115 points

Mar 31, 2008 11:47 AM in response to adsfushi72

Shutting down the computer at night should prevent the computer from freezing and roaring the fans, but only at night.
As for losing all your stuff, you can use Time Machine to back up your hard drive.

adsfushi72

Level 4

1,115 points

Mar 31, 2008 1:24 PM in response to adsfushi72

I've had the problem before installing Leopard, so this is a hardware issue.

I'm assuming you have to restart the computer by pressing and holding the power button when this happens. (That's what I have to do.) Whenever you shut down the computer like that, it's a good idea to test the hard drive, since forcing a shutdown can cause drive issues.
To do this, open Disk Utility, in the Utilities folder. Select your hard drive in the sidebar. The "First Aid" tab should be selected, but if it isn't, click on it.
Next, click "Verify Disk" and wait. The computer will become unresponsive for some time. Be patient.
If it reports problems, you will need to repair the hard drive. Start up from the installer CD and open Disk Utility. Repeat the above procedure, but press "Repair Disk" instead of "Verify Disk." It should repair any issues.
If it says that it could not repair the hard drive, back up everything and get the hard drive repaired or replaced by an Apple-Authorized repair technician right away.

Like I said before, I think you should be able to resolve this issue with a Terminal command.

adsfushi72

Level 4

1,115 points

Mar 31, 2008 1:42 PM in response to adsfushi72

You should have pressed "Verify Disk" instead of "Verify Disk Permissions," but verifying permissions is a good thing to do every once in a while.
After you're done verifying permissions, verify the disk.

Just to clarify, *verifying and repairing the hard disk will not solve the problem!* It's just a good thing to do after you force a shutdown.
I think opening terminal and entering "sudo pmset -a disksleep n" should solve the problem, where n is a number less than the number of minutes before your computer goes to sleep.

foertter

Level 1

0 points

Mar 31, 2008 2:32 PM in response to adsfushi72

wait hold a sec 🙂

this sleep thing I have to do once or every time I put the computer to sleep?

adsfushi72

Level 4

1,115 points

Mar 31, 2008 4:58 PM in response to foertter

No, no, no! Like I said earlier, this does not solve the fan problem. It's just good to repair the hard disk after you force a shutdown(i.e., unplugging the computer while it's still on).
Here's how to solve the sleep-fan issue:
1. Open System Preferences and find out how long (in minutes) your computer waits before sleeping. Remember this number.
2. Open Terminal.
3. Type "sudo pmset -a disksleep n" where n is a number greater than 0 but less than the number from Step 1.
4. When prompted, enter an administrator password.
I really think that this will solve the problem. Also, don't put the computer to sleep when there's much hard drive activity.

Apr 22, 2008 6:45 PM in response to adsfushi72

Subscribing, but I've also had issues. Since the upgrade I've had the fans thing once, but tons of apps just freezing and or quitting. iTunes and Firefox are the worst offenders, but Mail, and others have randomly quit or froze up. I have not done a clean install of 10.5, and from reading this, don't think I need to, but would love to see where this goes.

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