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10.4: Eliminate excess fan noise under 10.4.3 on G5s System 10.4
Tiger only hintAfter installing 10.4.3, I was dismayed to find that it had sent my G5 (a first-generation Dual 2.0GHz model) into the land of eternally cycling fans. Every few minutes, for seemingly no reason at all, the fan noise would ramp to near-max for a few seconds, then spool back down to idle. Watching with top, there was seemingly no cause for this activity -- no process was sucking up the CPUs, and everything looked completely normal. Needless to say, this was extremely irritating -- if you've ever heard a G5's fans at maximum speed, you know how loud they can be. It was so annoying I was contemplating downgrading to 10.4.2, just to get things back to a quieter noise level.

I tried the basics -- a simple restart, a SMU reset, and a PRAM/NVRAM reset. None did the trick. Then a friend pointed me to another possible solution he found at MacFixIt, involving (of all things) the Energy Saver preferences.

Open the Energy Saver System Preferences panel, and click the Options tab. Click the Processor Performance pop-up menu, and set it to either Highest or Lowest -- anything other than Automatic. Close the panel, and you're done. Not wanting to give up any performance, I set mine to Highest. I made this change on Friday afternoon, and since then, the fans have returned to their pre-upgrade behavior. They now only get slightly louder when I do something CPU intensive, and are at the same nice-and-quiet level the rest of the time.

Also see this hint for a possible solution if you have other noises in your G5 that you can't seem to explain or silence...
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10.4: Eliminate excess fan noise under 10.4.3 on G5s | 20 comments | Create New Account
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10.4: Eliminate excess fan noise under 10.4.3 on G5s
Authored by: delGrey on Nov 07, '05 06:17:14AM

I had problems also on my PowerBook G4 1.5 GHz on first installation. I then reinstalled from scratch and since then, utter silence. Bliss. No special settings needed. Maybe it was just a transient problem.



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10.4: Eliminate excess fan noise under 10.4.3 on G5s
Authored by: Arlo on Nov 07, '05 07:13:37AM

This may be a separate problem, but what is that electronic noise I hear when I move windows, or play full screen video sometimes? It's really annoying...any fix for that?

---
www.automatorworld.com
"Better Living Through Macintosh Scripting"



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10.4: Eliminate excess fan noise under 10.4.3 on G5s
Authored by: metrazol on Nov 07, '05 09:48:31AM

That, my friend, is the bane of sound engineers on PCs since the bane of time. The buzzing is caused by the bandwidth limitations off your PCI bus. When you move windows the graphics card is using it's "hardware acceleration" to make things snappy, which introduces noise into the sound card b/c of the limitations of the PCI design. Of course, with hardware acceleration turned off for 2d operations, it goes away, but whether that'll work under OS X, I don't know. The hardware gurus have promised a fix for this every year since PCI came out, so don't hold your breath. It's much, much worse on Windows machines, but a number of good sound cards can avoid this, and many MoBo audio chipsets. Sorry, but you're stuck.



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10.4: Eliminate excess fan noise under 10.4.3 on G5s
Authored by: bailey_ca on Nov 07, '05 07:24:02PM

AFAIK, this is not just limited to the PCI bus; my old (very old) 386 used to do this as well, using just ISA cards.

You're right, it's generally much worse on PCs, likely due to the plethora of components they use. For example, the built-in sound card on my relatively modern PC produces a horrible amount of electronic "chatter", even from hard drive access. Installing a SB Live reduced the noise substantially. Better circuitry or RF shielding?

(The novelty of hearing the squeaks and blips of hard drive activity quickly wears off when you're listening to music and Windows is busy swapping in and out of the pagefile.)

At any rate, I always found the best fix was to use the amp in your speakers instead of the sound card. Cutting the sound out volume in half and the turning up the speakers did a great job.



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10.4: Eliminate excess fan noise under 10.4.3 on G5s
Authored by: Pyrrhus on Nov 08, '05 07:39:59PM

Maybe you are talking about the problem by having "nap" mode enabled? On G5s this mode issues a very annoying high-pitch sound on certain operations. Anyways, you need to download the CHUD tools at Apple and disable nap mode to fix the issue.



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10.4: Eliminate excess fan noise under 10.4.3 on G5s
Authored by: samkass on Nov 07, '05 08:05:56AM

Unfortunately, turning off Nap doesn't make all my G5's chirping disappear... I had to put it in Automatic to make it completely quiet. Now that I have to set it to Highest to make the fan noise go away, I'm in a no-win situation with my G5's noise.



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10.4: Eliminate excess fan noise under 10.4.3 on G5s
Authored by: mm2270 on Nov 07, '05 08:13:55AM

The chirping sound is a separate issue, which is addressed in this hint, also appearing today:

http://www.macosxhints.com/article.php?story=20051106072241470&lsrc=osxh

I don't have the fan cycling issue, thank goodness, but I do get the chirping, so first chance I get I'm going to give this hint a try.



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10.4: Eliminate excess fan noise under 10.4.3 on G5s
Authored by: samkass on Nov 07, '05 12:29:20PM

Yes, but as I said, MacOS X Hints got it wrong on that other article. "Nap" mode only silences the most noticable chirps... Automatic mode makes the power supply and audio-line feedback completely silent. But now makes the fans go crazy. :(



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10.4: Eliminate excess fan noise under 10.4.3 on G5s
Authored by: G5Dude on Nov 07, '05 12:30:36PM

I also ran into this problem on my 1st Gen Dual 2.0GHz. I don't know about any of you with AppleCare, but I was told over and over again by AppleCare reps that "Apple is aware of the problem and working on a fix." I went through 2 power supply replacements, CPU replacements, graphics card replacement, and had all the fans replaced. No luck.

Then a month ago they changed their stance to "this is normal behavior for this model." Obviously, this was unacceptable. I asked to speak with someone from Apple Corporate Executive Relations, and after a bit of back-and-forth they agreed it was not proper treatment. They decided to replace my 1st gen dual 2.0GHZ with a dual 2.3GHz equal to my original purchase value (RAM, video card, etc).

The new machine still has a bit of the chirping, but not nearly as badly and most importantly the sounds do not appear to leak into the analog audio-in and audio-out. I can't guarantee this will work for everyone (or anyone really, maybe they were in a nice mood when I called), but it's worth a shot!



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10.4: Eliminate excess fan noise under 10.4.3 on G5s
Authored by: jeffulri on Nov 07, '05 03:46:37PM

Similar problems (fan stuck on HIGHEST cooling setting) on an iMac G5 (Rev:A) 17-inch w/SuperDrive after moving to 10.3.4 - followed all the instructions elsewhere to no avail (replace .ktext, check ownership/permissions, Zap PRAM, reset Open Format, etc.). A PHYSICAL reset using the internal hard reset buttons for the PRAM/NVRAM (at least, that's what I ASSUME they are) got rid of the problem and allowed me to continue to use the Processor Performance AUTOMATIC setting without inappropriate fan ramp-ups. Your mileage may vary.



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10.4: Eliminate excess fan noise under 10.4.3 on G5s
Authored by: pecosbill on Nov 07, '05 04:05:33PM

The SMU info above is incorrect. The First Gen Dual 2GHz G5 does not have an SMU, but a PMU which requires a different reset procedure. Apple's site only says to check your manual for the reset button's location.

Keep eyes peeled all over (like macintouch.com, macfixit.com, etc) to see what works for others. Not everyone had to resort to Highest processor.

---
Pecos Bill



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Something to Keep In Mind
Authored by: Makosuke on Nov 07, '05 06:06:37PM

Just a reminder, while setting the processor speed to "Highest" will result in quieter fans (as it did under the one 10.3 update that caused a similar random fan cycling issue), remember that your G5 will draw somewhat more power in this state and thus cost you a bit more money on the electric bill, so even if this resolves the issue it's worth keeping an eye on MacFixIt or wherever for more permanent fixes.

Also, I'm going to have to look at that post above referencing that the very first-gen PM G5 DOES have a PMU, and as such a PMU reset button as opposed to the SMU (which is reset by unplugging the computer for 15 seconds). Perhaps this is why the SMU reset procedure isn't working for some while it is for others.

The button, according to the web, is at the very bottom of the motherboard, under the processor fan assembly (a bit below the lower RAM slots). I'm going to have to crack mine open at home and see if this works--perhaps that's why the SMU "reset" I did didn't fix the issue...



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Something to Keep In Mind
Authored by: Steve_G on Nov 09, '05 06:15:40AM

In my 20-inch iMac G5 the PMU reset and power testing buttons are next to each other--small, gray, about the size of an o in 12-point type. You can turn onthe machine and test the power supply by pressing the innermost button and see the little LEDs light up (there are four of them, but I forget the code at the moment). When I started that way (with the case's back removed) and then pressed the outer button, the fans quieted instantly, and now they are well-behaved.

---
Steve_G



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What worked for me when all else failed...
Authored by: JPBankston on Nov 07, '05 11:15:00PM
I tried every hint given from resetting NVRAM to playing around with the Energy Saver control pane. Nothing worked - my fans were at full speed all the time. Finally, I read this hint at macintouch about disconnecting the power cord and voila my iMac is silent once again.

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What worked for me when all else failed...
Authored by: johnsawyercjs on Apr 25, '07 12:34:27AM

That hint, for which only one step is to unplug the power cord, is the process of resetting the Mac's SMU (System Management Unit) chip.



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10.4: Eliminate excess fan noise under 10.4.3 on G5s
Authored by: Apple&Pears on Nov 16, '05 08:54:21AM

Hello....I just want to thank you very very much for the information about the fans reving up on the OSX G5 after the update to 4.3....I had the same thing happen to me. After contacting Apple Tech Support (many times) and doing an Archival Install, throwing Cache Files to the Trash, nothing worked. Even in a "Test Users Account", the problem persisted. Their final suggestion, was to totally clean my Hard Drive and then do another Install. This would have involved buying hardware(LaCie Hard Drive) in order to back up data. The problem with my Fans reving up has been ongoing until today, when I finally read in Mac OSX Hints and saw the problem and solution addressedby you. Your solution regarding Energy Saver has WORKED. It is too bad that no one in Tech Support knew about this. I am sure that other people are having the same problem. Thankyou.



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still having (terrible) fan noise one month on
Authored by: oliverlangan on Dec 05, '05 10:07:32PM

Over a month ago, when the 10.4.3 update was just released, there was a flurry of complaints on many mac-related message boards about increased fan noise. I had the same problem on my iMac 20" at home and my PowerMac G5 at work, and tried all three solutions that I found online:
* change the processor performance setting in the Energy Saver preferences pane
* completely unplug the machine for (up to 10 minutes), plug it back in while holding down the power button, then release and press power again (SMU reset)
* resetting several options in open firmware

None of these worked for me, but my work machine is far enough away (and in a noisy environment) not to have bothered me. My new son was two months old and not sleeping through the night, so I barely used the iMac anyway.

Now, however, he is sleeping through the night and the iMac fan noise has become terrible. When catching up on my TiVO watching via EyeTV, the fan noise gets so loud it sounds like being inside a 747 jet (though admittedly without the low base rumble). I can not hear the audio of the programs, and have to resort to Closed Captioning. The same is true when playing some games, notably World of Warcraft. I can definitely say that these activities were much, much quieter before: and that the fan took longer to activate when it did come on.

In most cases I have noticed, MenuMeters shows the actual processor usage to be quite low: but the applications are graphics intensive. I wonder if perhaps the fans could be keyed to the usage of the graphics chips, not the main CPU.

Has anyone else been plagued by these long-running fan issues? Has anyone with an iMac G5 (20", no-builtin-iSight model) managed to get rid of all traces of these fan issues?

oliver



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still having (terrible) fan noise one month on
Authored by: airsine on Dec 15, '05 03:12:25PM

I'm running a 20' G5 imac and the fans are driving me mad. There doesn't seem to be any link between the amount of data being written/read to the HD or the CPU temp and the RPM of the fans. I hope the next update sorts this out.



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still having (terrible) fan noise one month on
Authored by: oliverlangan on May 17, '06 10:38:15AM

Well, eventually I took my iMac G5 (2gHz, no iSight) to the Genius Bar in SF and told them exactly all the things I had done to eliminate fan noise. The girl working on it said "well, I guess there is no need to diagnostics!" and they took it in and swapped in a new logic board.

That was about 2 months ago: the machine was wonderfully silent at first, but now, alas, the fan noise is coming back. I have tried all the tricks again, but they don't last for long: last night just reading email was enough to kick the fans into high gear! Armed with my knowledge that Apple _knows_ about this problem, and the fact that they fixed it once before, I am headed back to the Genius Bar. Thank goodness I got AppleCare on this unit.



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Eliminaing fan noise on G5s
Authored by: JonS on Aug 25, '06 08:45:41AM

There is another reason why the fans in a G5 will come on and stay on constantly for no reason (in particular especially after start-up) and it's decidedly low-tech.

If you've removed the clear plastic air deflector while delving into the internal workings of the G5, you may have damaged the white metallic self-adhesive strip attached to the lug at the base of the deflector. I think this strip forms part of a circuit which tells the G5 that the deflector is in place (as it should be) when the power is on.

A damaged strip breaks the circuit and convinces the G5 that the deflector is missing while the power is on and components are in danger of overheating. In response it switches all fans on to full. Smoothing out flat a wrinkled or torn strip can solve this problem.



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