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Another way to control CPU napping System 10.4
The hint titled Possibly eliminate 'chirping' sounds from G5 CPUs describes the use of CHUD to disable CPU napping, in an attempt to suppress 'chirping' sounds when the system is idle. One drawback to this method is that it's not persistent, requiring an AppleScript startup item to turn off the CPU nap flag.

Apple recently released a new version of the CHUD Tools (described near the bottom of the page; or just download from the CHUD FTP server), which provides a command-line tool called hwprefs that, among other things, allows the root user to enable or disable CPU napping.

I won't enter a debate as to whether it's better to create a StartupItem or add a line toward the end of /etc/rc to handle this, (or enter a debate as to whether or not it's a good idea to disable napping in general), but using this command...
hwprefs -v cpu_nap=false
...in either a StartupItem or /etc/rc will disable CPU napping at startup.
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Another way to control CPU napping
Authored by: rspeed on Nov 15, '05 06:35:18AM

Or a launchd service (for the Tiger users). :)



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Another way to control CPU napping
Authored by: wackazong on Nov 15, '05 07:38:09AM

Could you tell me how to do that? I have not used the launchd before..

Thanks!

ALEXander.



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Fixes same problem on PowerBook
Authored by: triplef on Nov 15, '05 08:18:23AM

Interesting stuff, I also have these chirping sounds with my PowerBook 1.25 GHz, and the command also disables the chirping.
However, I would be really interested if anyone could comment on this "processor nap" and the possible changes when disabeling it. After I had disabled the napping, it took about 2 minutes until the fan of my PowerBook was switched on, so it seems it disables some powersaving (and thus heatsaving) features of the processor.



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Where do chirping sounds come from?
Authored by: triplef on Nov 15, '05 08:21:57AM

It would also be interesting if anyone could comment on why napping can result in these chirping sounds.
Thanks! :)



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Another way to control CPU napping
Authored by: bnew on Nov 15, '05 09:15:27AM

CPU napping is when the processor dynamically "slews" the power usage up and down, according to how much work the CPU is doing. This is why you hear the chirping sound when you suddenly do something CPU intensive (like activating Expose). Once the CPU has slewed the power consumption up, it will stay up until the CPU usage drops.

I've been disabling processor napping on my G5 since I got it (October 2003) and I have yet to see any adverse effect on my machine. That noise drove me crazy from day one, so I found the CHUD tools back then and wrote myself an AppleScript to eliminate it on startup.



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Another way to control CPU napping
Authored by: djdawson on Nov 15, '05 06:42:11PM

I've noticed that when I turn off napping it makes about a 10 degree C difference in the CPU die temperature reported by "Temperature Monitor" (I have a dual 2.5 G5). Whether this is a problem or not isn't clear, but I've decided that until the chirping bothers me I'm going to allow nap just in case.



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Another way to control CPU napping
Authored by: interlard on Nov 15, '05 12:58:18PM

I never noticed the noise coming from my PowerBook until one of the Panther updates. Then it drove me crazy.

Is this just a hardware "fact" that can't be avoided, a piece of sloppy hardware design or can the noise be reduced with a software fix?



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Another way to control CPU napping
Authored by: Unsoluble on Nov 15, '05 05:09:18PM

Hmm. Every time this chirping thing comes up, it's reported as being associated with high CPU activity, or at least as a sporadic sort of thing...

Mine's quite the opposite, though: I've got a dual 2.0 G5 from last summer, and if I don't disable napping I get a very regular, very audible chirp roughly every second. Chirp, chirp, chirp, chirp, ad nauseum. Can't stand it, so I turn napping off. But if it was only periodic, I might be able to handle it.

Nobody else has just the regular chirp?



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Another way to control CPU napping
Authored by: SethTisue on Nov 16, '05 05:51:20AM

My dual G5 tower has both the regular chirping, and irregular chirping during activity. Until I read the threads here I always assumed the regular chirping was coming from the fan, but disabling CPU napping makes both kinds of chirping go away.

I find this whole issue rather surreal... I mean, I understand how a fan or a hard drive could chirp, but the CPU...? I'd really like to understand this.



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Another way to control CPU napping
Authored by: gesundheit on Nov 16, '05 10:08:17AM

Yes, the only extra noise I get is a fairly quiet beep once a second when activity is low, and is fixed by unchecking "allow nap" in processor prefs (part of CHUD tools).



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Another way to control CPU napping
Authored by: lucidsystems on Jul 10, '06 04:33:52AM
This link may help you.

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Another way to control CPU napping
Authored by: @1 on Nov 16, '05 03:58:32AM

Great tip. I couldn't believe just how much quieter my studio speakers are having turned off napping.



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Another way to control CPU napping
Authored by: Arturia on Nov 22, '05 06:21:28AM
An easy way to run this script at login is to download an already existing login item, as Broadband Optimizer
http://www.enigmarelle.com/broadbandoptimizer.py

and add this line to the BroadbandOptimizer config file:

/usr/bin/hwprefs -v cpu_nap=false > /dev/null

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Another way to control CPU napping
Authored by: lucidsystems on Jul 10, '06 04:07:23AM
There is solution....
An easy to install startup item

Definitely have a look and see if this fixes your problems.
Apple if you are listening, please look at addressing this issue, all the apple forms on this topic have been archived. Is this still an issue, or is it resolved?

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