CHUD Updates: are available via the Chud Updater util or checking the Apple FTP Developer Tools directory (was ftp://ftp.apple.com/developer/Tool_Chest/Testing_-_Debugging/Performance_tools/). See the readme file in the download for the list of changes. (If you have CHUD already installed, use the CHUD remover utility before installing any updated version.)

Note: See the report below from a Dual G5 owner that said Apple told him they do not recommend disabling Nap mode (but I'd love to see their concrete reasons on how it could cause harm if the system is designed to run taxing apps for extended periods of time which load the CPU heavily).

Some Noises Fixed? (from the March 4th, 2004 www.xlr8yourmac.com news page). Cnet (March 2004) posted an article titled Apple silences beeps, hissing that says Apple confirmed that the latest G5s coming off the production line have a fix for the noise problems reported in the past. The article mentions only Dual 1.8GHz systems, but since the first G5 shipped last fall we've covered the PS noise (chirping/squealing, etc.) here (this page) with the tip on using CHUD Tools Nap mode to prevent the squealing/chirping noises. (The noises they are referring to in the cnet article may be a different issue.) I and other G5 owners had a Power Supply swapped last fall that didn't help with the chirping/squealing issue (if Nap mode was enabled), but the latest power supplies are almost certainly a later revision than what we have.

Dual G5 Owner Comments on Pwr Supply Swap: (from the Oct. 16th, 2003 news page) A Dual G5 owner wrote he's gotten a replacement Power Supply that he hoped would solve the Chirping/Beeping noises without requiring disabling "Nap" mode using CHUD Tools. (It didn't - I had my Dual G5 PS swapped also due to a noisy fan, and the chirping/squealing at times is still there.) He also said he was told that Apple does not recommend disabling Nap mode (how that could cause any damage is beyond me - if the G5 is designed to run taxing apps for extended periods of time then disabling Nap mode I wouldn't think would cause any problems)

" my G5's internal HD went bad, and I lost everything. In the days since, I've had some interesting experiences. To make a long story short, Apple agreed to send me a replacement HD AND a replacement 600W power supply for my Dual G5 (apparently there are two separate power supplies - a 450W for the singles, and a 600W for the duals). The AppleCare rep on the phone confirmed that the power supplies were the culprit (on the Duals) for the 'chirping/beeping' noises, and that they were quietly replacing them to people who complained.
The rep also noted that internal AppleCare docs mandated that the reps tell people NOT to use CHUD tools/Nap fix to solve the problem -- apparently it is NOT good for the system. I asked if she could/would send me that doc in an email, but she wasn't able to. (again I really don't see how that can damage a system - but if Apple can explain why/how it can I'm all ears.)

In any event, the replacement power supply arrived today via express mail. What baffles me is that it clearly says "for sale to apple authorized service providers only" on the shipping label -- I'm rather surprised that they sent it directly to me. I spent some time prying open my G5 to see how difficult it would be to get the old power supply out -- it is VERY VERY tricky. I suppose I'll have to take it to an authorized provider, but I'm afraid to be the first dual G5 somebody sees/works on. If you know of any documentation on getting that sucker out, it would be appreciated. If I get brave and decide to remove it, I'll document it so you can put it on the site. I've attached some pics of the Power Supply. Let me know what you think.
I asked for info on the P.S. (marking/part no. revision, etc.) and what S/N is G5 was and he replied)

The new PS has the following:

Brand: AcBel
API2FS34
ID: 291
DATE: B0339
REV: C
APPLE P/N: 614-0271\
Made in China
serial#: FZ339DRPQ9ZA

My G5 is in the "XB338..." range."

Note: He later said his original P.S. was a "rev A", but that the rev C Power Supply didn't change the "chirping" noises. (I wonder what the rev B and C changes were - and if they have higher quality fans.) I don't know of any Apple (public) docs that cover the PS removal. Power Mac G5 CIP (Customer Installable Parts) Instructions (http://docs.info.apple.com/article.html?artnum=26276, no longer online) - from Apple's G5 CIP page covers only components they consider end-user installable. (Update - A single G5 owner wrote with a link to his page on replacing a noisy fan in the (single CPU) G5 P.S. - the Dual G5 model would require removing a CPU module/heatsink.) It turns out my loud humming/aquarium pump-like noise is coming from the PS area. I suspect a noisy P.S. Fan is the culprit.
Like the new Powerbook latch/display problems, buying the 'first revision' of any new model is more risky but I don't follow my own advice. I can't say as I hear the beeping/chirping noises on this Dual G5 but the humming noise from the upper area (HD/HD fan area) on my machine is loud enough to mask it I suspect.

CHUD Tools Tip for G5 Beeping/Chirping Noises: For those that hear beeping or other noises (chirping-like sounds when moving windows, hiding/unhiding the doc, etc.) using Apple's CHUD tools to disable "Nap" mode seems to help. Here's a sample reader mail with the tip:

"I read on another help page that a fix for this problem is the following:

The solution requires that you download Apple's CHUD tools, which are available from
ftp://ftp.apple.com/developer/Tool_Chest/Testing_-_Debugging/Performance_tools/
(3.0 direct D/L link removed after file removed when 3.0.1 update above released.)

After installing CHUD, go to System Preferences, open the "Hardware" pane and turn off "Nap".

Apparently this option turns off the G5's ability to use processor idling, eliminating the beeping noise.
Hope this helps those with the problem. I don't have any such problem with my dual processor 2.0GB G5.
Wayne S. "

Reader feedback on this tip is below, including links to recordings of the "chirping" noise (during dock hide/unhide), the beeping noise and a recording of the effect of enabling and disabling Nap mode (on the fly).

Reader Reports on G5 Noise and/or CHUD Tools Fix: (most recent first - updates appended to some previous reports.)

Applescript tip for Disabling Nap Mode on G5 at Boot: As mentioned before here, the disable Nap mode setting does not stick after a reboot. A reader sent a note/tip on using Applescript to disable Nap mode automatically at each startup:

" One thing I noticed (with CHUD 3.0.1), and it might have been in the previous version and I missed it, there is a command line version of the preference pane.
From a terminal window, you can enter:

hwprefs cpu_nap=false

to turn off the nap and the noises.
Expanding on this, a little Applescript droplet can be created and added to the login items preference so that napping can be turned off automatically on restart or reboot:

do shell script "hwprefs cpu_nap=false"

Save as an application away you go.
John T. "

"Oscillating Buzzing Noise (OBN)" (includes updated comments from 10/16/2003)

(update added Oct. 17th, 2003)
"As you may recall, last week i sent you a .m4a file of the sound and now i have the solution for this problem (more or less). the drum beats on and more people are posting all the time about this problem. the thread on the apple discussion forum has the most of any G5 topics, 155 right now.

I hope for this to be the penultimate episode in my ongoing saga, battling against the oscillating humming noise of my new dual G5. here it is:

last week it was posted on theapple forums that--if one were daring--one could in fact touch, and thus stop, the front fans on the power supply one at a time, by reaching finger around the bottom shelf of the inside of the G5. i used a flashlight pressed up to the grill to verify that the fans were in fact there, and then reached my finger down into the abyss, and in fact it was fairly simple, and i can say from experience (as the first thing i did was hit a spinning fan blade, and it was nothing) that it is not dangerous. i then pressed down on the hub of the left fan until it stopped and there was no change in the OBN, and then i stopped the right fan and--
hallelujah!!!

--for a few brief moments my G5 sounded like it was supposed to sound. and it was quiet, sweetly quiet, and then of course i let go of the fan and the OBN came roaring back. the OBN makes the computer AT LEAST three times as loud as it was with the fan stopped. it was a great moment because the mystery had been solved, and now i had a new challenge: how to fix it (or more properly, how to get it fixed).

a few days after i discovered that the right front power supply fan was the source of all the noise, i finished the print project i was working on and called apple again. as you may remember on my first call i was blown off and told to take it to a authorized service center (there are none closer than an hour to me) and they would 'look' at it. i balked at that because this is my work machine and i couldn't sit around for a week or more while they evaluated it, then ordered a part, then waited for it, etc. my second call was much more successful, i assume mostly due to the fact that i now knew exactly what the problem was. i explained the problem in detail to the tech support guy, who was very nice and polite, and also explained why i needed a solution to get this fixed with only a day or two of down time. he checked and found the part number for that particular fan, and confirmed that it was NOT a customer-installable part. he suggested that a service center could order the part ahead of time, and that i could just bring the G5 in and have the fan replaced. he gave me a case # that would smooth the ride at the service center, and i thanked him for being so helpful.
i then called my favorite mac store in salem, oregon (the computer store) told them of the plan and the case#, and scheduled to bring it in next thursday and get it back by friday night (hello, panther?!). they ordered the part today and we should be in business.

so, everything is lined up for this problem to be remedied, for me at least. i will let you know how it goes, and if it does, in fact, solve the problem.
thanks!! paul

(his previous report added Oct. 7th, 2003 follows)
" i have had my dual G5 for 6 days now, and since the first day, first minute, it has emitted a weird Oscillating Buzzing Noise (OBN). Everything is working fine, I have added two gigs of memory on four chips, and added a second maxtor 160gb drive. i have the chirping sound that many others have reported on xlr8yourmac.com, but it doesn't really bother me. i can also hear the very low fan noise, and that doesn't bother me either, and when the hard disks do spin, i can barely hear them at all. ahhh, but the damn Oscillating Buzzing Noise (OBN) keeps coming, unrelentingly and it is driving me crazy.

i was hoping that after a few days it would go away, or i would get used to it, but that hasn't happened, at all. the sound in detail: it is a type of constant electronic hum, that oscillates, similar to a 'beat'--when two frequencies are similar but not exactly the same. waawaawaawaawaawaa, etc. about two beats per second. it is not the noise of air turned by fans, and the sound is very much present even when both hard drives are spun down. i have the 9600 pro which has no fan. pressing my ear to the front, back, and open side of the case it seems clear that the sound is coming from the bottom half of the machine. to see if it was something to do with the four fans for the two processors i (don't try this at home) reached in the case and manually stopped the fans very briefly one at a time to see if it affected the sound, and it did not. at this point i am fairly sure it is coming from the bottom thermal zone where the power supply is, which of course, i have no easy access to. this Oscillating Buzzing Noise (OBN) is by far the loudest sound coming from the machine, much louder than the fans, or the aforementioned chirping sound.

anyway, i have realized that it just won't do, as it continually aggravates and distracts me, similar to poe's tell-tale heart but without the murder, and as such an innocent i am going to talk to apple and try to get this fixed, but i first wanted to see if anyone else has a similar sound, and what their experience has been with it. mainly i want to try and figure out if this is how they are supposed to sound out of the factory, or if mine has some type of defect. until then i (seriously) have a table fan turned on next to my computer to mask the annoying Oscillating Buzzing Noise (OBN). tales of y'alls experiences are greatly encouraged.
Paul M.
(he later wrote)
well, i did some searching on the apple forums and found three others who are having the same humming noise problems as me, which is actually fairly comforting. one has even sent his back for apple so they can replace the power supply.
here is the link to the discussion (old forums link) on the apple site, if the link doesn't work, search for "power supply humming"
they all agree that is is exceedingly annoying and it looks to be a defect that at least a few people have, so if anyone out there was thinking it was standard, it is not! send it back! i'll be calling apple tonight.
thank god, i was worried i'd have to put up with this noise forever. "

I hear a constant humming noise - which seems louder now than when I first bought it but then maybe I just didn't pay that much attention originally. This sound however seems to be coming from the upper area, near the hard drive/HD cooling fan. I don't hear it in the lower area and it's not the 9800 Pro (retail) card fan. I tilted the plastic shield out a bit and temporarily stopped the 9800's fan - that's not it. It really sounds like it's coming from either the hard drive or the fan that cools the hard drive. It does not Oscillate however (steady hum).

"I was the one who started the thread on this at Apple's discussion pages. While I called Apple today to see if installing the CHUD was an official or endorsed fix, they said no, but I could certainly go ahead and do it anyway.
So I did, and I am happy to report that it did make the beeping go away. The only side effect is that the fans run slightly faster now, but the noise from the fans is both quieter than most computers, and much better than the beeping.

Still hoping Apple can address this in a firmware or OS update, as I don't really think its fair to force average consumers to install developer tools to make an annoying sound go away.
Great site by the way!
Craig H. "

" Just one last note on using the CHUD tools to disable the "Nap" feature on the Dual G5: restarting your machine re-enables "Nap." You may have already seen this on Apple's forums. Kind of a bummer - although, I rarely turn my machine off. In any case, running with "Nap" turned off today seems to have resulted in a noticeable increase in general speed/responsiveness for me (I'm still running the stock 512MB RAM, with another 1GB on the way).
Matthew S. "

" Just want to add my name to the list of Dual G5 owners that have the beeping and the "electronic" scratching sound when processor/disk activity is high. I noticed the second noise when I did a Repair Permissions.

The CHUD tools does fix the problem and quiet the machine and I haven't noticed the fans coming on more or faster.

However, the NAP feature in the control panel does NOT persist across a reboot. I have to turn it off when I start up the machine or reboot.
john "

" i had a G4 dual; 1.25 a week ago...now with dual 2 G5 ...buzzing sounds from the speakers have been almost a trademark with Apple...My Ti800 / Dual G4 FW800 and now dual G5 all do the same...
those computers all used some kind of energy saving features for slowing down processor/fan...maybe thats the cause....
thx for your great site, keep up the good work Felix "

Apple had a kbase doc in 2003 on MDD G4: Balanced or Grounded Equipment Has a Humming or Buzzing Noise (http://docs.info.apple.com/article.html?artnum=75408 - no longer online) and I thought there was some note about powerbooks/ibooks related to energy saving mode (turning off the audio) causing some initial noise, but I can't remember the details now. Then there was the previous issue I mentioned from the past (audio noise during airport networking, at least with high speed connections/downloads).

" I did some more testing. The USB behavior seems to have been a fluke -- while it did stop the noise for the rest of the night, a restart brought the noise back. I haven't been able to replicate the fix by plugging/unplugging the hub. Bummer.

(here's a clip from his previous mail on the USB Hub/noise issue)
" I have a 4-port belkin USB hub, and I have 3 devices plugged into it: a CompactFlash (sandisk) reader, an Epson Perfection 1660 Photo Scanner, and the aforementioned Logitech USB digital microphone. While laying on my back, listening to the beeps/pulses, I unplugged the hub from the back of the G5, and the beeping stopped immediately. (but he noted above that unplugging isn't a fix) "

In apple's forums, many people noticed a "chirping" noise when you show and hide the dock (dock is set to hide automatically). I also noticed this today. (I don't hear this on my Dual G5 - unless it's so subtle that I can't hear it even with my ear close to the G5 lower front case.) I got out the logitech mic again, and recorded it. This AIFF sound is of me hiding and revealing the dock over and over again. It kind of sounds like a high-pitched cricket. It is also much louder than the "pulse" noises -- this I can hear without getting down under the desk. It also happens when I am dragging a window around the screen. Again, there is a lot of ambient noise in the normalized audio, but if you listen you can hear the "chirping" when I show/hide the dock. Pretty weird... here it is:
http://homepage.mac.com/rayman/dock_chirp.aiff (page no longer online)

http://homepage.mac.com/rayman/G5_beep_original.aiff (page no longer online)

I'll be installing the CHUD tools today and see if it fixes the problem. Also - I had said before that there was no noticeable difference in volume when I changed the slewing mode -- I tried it again this morning, and there is a definite (but slight) change in volume, louder on "Highest" and quietest on "Reduced".
I'll let you know if anything else crops up.
Matt
(he later wrote this morning)

I just finished installing the CHUD tools. I went into the new "Hardware" system preference, and checked and un-checked the "Nap" checkbox. Sure enough, as soon as I un-checked the box, all of the noises went away.
If I re-checked the box, the noise came back. I've recorded this as well, so here is yet another AIFF file -- In it I start out with the "Nap" checkbox CHECKED, and then I click on it several times. This is the clearest audio I've been able to get, so it's easy to hear how the noise cuts out and back in again (you can even hear the mouseclick when I re-check the "nap" box).
http://homepage.mac.com/rayman/nap_on_off.aiff (page no longer online)
Curiouser and curiouser.... I'd like to think it won't be a problem to leave the "nap" setting off, but I'm not optimistic. (it may make the fans run more often or faster) Here's hoping Apple can fix this in firmware... I would imagine to serious audio folks, this kind of high-frequency noise would be a real issue.
Let me know if there is anything else you'd like me to try. Thanks!
Matt "

" I have also experienced some strange noises with my G5 Dual.
Config: 1,5 GB ram (2x 512, 2x 256 all cl3), Superdrive, Radeon 9800, Airport Extreme, 160 GB Voltage 220 V, as I live in Germany

Noises:
Startup: three small "bubs" seems to come from the speaker in greyscreen. (I hear this also - very low volume and only at the very end of the gray screen, just before the blue desktop starts.)
Running: pulsating high-pitch sound from the bottom of the g5, quiet but hearable at automatic, quite loud on highest. I think i will try the CHUD-fix!
Thanks for all your time making xlr8yourmac so unique.
Cheers, Maik "

" I have a Dual G5 that's affected with the scratching noises. No clicks, no continuous buzzing; only a faint scratching noise when scrolling and when showing/hiding the dock. Unlike other reports in my case the sound persists (only fainter) on the Automatic and the Reduced processor settings.
Installing CHUD and turning off Nap completely eliminates the scratching, turning on Nap brings it back.
The noise never bothered me (in fact I thought it was kind of cool, even briefly considered it might be a system sound).
D.J. "

(Updated Oct. 7th, 2003)
" G5 1.8 stock config, 1024 MB Ram. No noise what so ever except for the CD Rom spin up at Start up for about half a second. No click or ticks except the one I do with my mouse, My energy setting is set to "highest"
Aharon
(he later wrote)
Since I last wrote, I now hear the sound. I had to restart my G5 for the first time in 2 weeks. The "NAP" reverted to On, and while working in Photoshop I heard a high pitch sound every time I scrolled horizontally. I went and put my ear by the bottom of the CPU while I scrolled and sure enough there is a sound the comes from the bottom of the machine. It also sounds when I use Safari. It's not that laud, but when working at 2am in complete silence it can get a little annoying.
aharon "

" I have a stock G5 dual-processor machine that was making squealing noises when opening/closing windows, dropping down menus, etc. The noise was at it's worst while transferring large files across the network.
I downloaded/installed the CHUD tools, turned off NAP, and PRESTO - instant quiet G5. Not sure I understand exactly why it works, but it sure does. I plan to keep it off for several days to see if there are any undesirable side effects.
BJ "

" i am also getting 2 different kind of noises from my new dual G5 with BTO Radeon 9800 Pro.
the first one is the steady sound when processor performance is set to highest... but this is REAL soft and does not annoy me at all - you have to be really quiet to hear it at all...!

the real problem has to do with video or open gl and mostly happens here in Cinema XL 8 (demo at http://www.maxoncomputer.com/) : in the preferences set the viewport-options to OpenGL Shading (it does not happen with software-shading)
with this option enabled i get a LOUD high-pitched noise everytime i resize the screen. grab the side of the work-area and scale it and the mac really starts to "sing". this is annoying!

I do not know where this sound is actually coming from, but it does not change at all when i change the volume of the G5 - it's constant and reproducable!

but these sound are not exclusive to cinema, when starting the quicktime-player for the first time there is this sound, too and i have heard it in other occassions, too
greetings, Jan S.
(I suggested he try the CHUD Tools to disable Nap mode and report back if it helps.)
wow, this actually works !!!
I did not believe that this helps with the cinema-noises, too, but its true: ALL noises are gone!
now i would love to hear some official words from apple about possible downsides of diabling NAP...
thank you, jan s. "

" turning off nap fixed my problem.
Thanks a ton
Adam "

" My DP G5--a standard system with 9800 Pro OEM card--has no beeping or pulsing that I can hear even when set on Highest performance. (Mine doesn't either that I can hear, other than the *very low volume* almost 'click' sound at the end of the gray screen that you really have to listen for to notice.)
Also, re: the fan errors, I ran the Extended hardware tests the day my machine arrived--two weeks ago today--and I received no such errors. (Mine either - passed all tests w/HW Test 1.1.)
-Dion "

" i got the dualie, and i hear the pulse/beep (approx every second) with the default energy setting (automatic, i believe). i haven't experimented yet with other energy settings...
Keith M. "

" I have been experiencing these noises as well. One other comment to this. I had a Mackie 1604 Mixer connected to a pair of powered Alesis monitors and (even when not connected to the G5 at all) I can hear this same noise coming from the Mackie. Whatever is causing the noise, it seems to also be creeping out out of the power supply and is being picked up by other external devices.
I noticed when playing a song with iTunes that it makes the audio sound distorted because of all of the screeching electronic type noises coming through the Mackie.
David
(I asked if he had tried CHUD tools to see if that affected this (disabling Nap mode) and he replied)
I tried the CHUD tools and it reduces the noise considerably but it does not eliminate the noise. Although, I have to really crank the volume to hear it. "

" Noticed your mention of odd G5 noises. Mine (on a dual G5 with 2GB RAM and two 250 GB drives) involves an almost "electrical" buzz that only occurs after lengthy use. Oddly, tapping on the case or pressing on it stops the buzz (momentarily). Perhaps something gets hot as time goes on and rubs against something. At any rate, it sounds electrostatic more than anything.

My biggest problem with the G5 is a certain mouse "latency" I'm having. The mouse sits there sometimes refusing to move. (Apple replaced the white mouse with a white Pro mouse just two days ago.) But the latency persists to some degree.
(He included a repeat of the CHUD Tools tip to disable Nap mode, clipped to save space)).

Since I'm no developer, I am hesitant to use CHUD tools. (I really don't know what they are and if I could do any damage.) Still, I would like to see how this story develops.
Thanks for this and all the great info your site provides.
BK "

" When ever I go to the dock and the dock unhides, i hear this sharp noise like a mouse squeak. I Hear the same noise when the dock auto hides and some times when i open windows. And i just noticed that it does it the entire time i am minimizing a window (even the entire time when doing it in slow motion by holding shift). It is much louder when performance is at highest.
Thanks for the great page -Adam
2x2 g5, 9800, 2.5gb "

I asked if he had tried the CHUD Tools tip.

" Just received my new dual G5 today and there*s a very annoying noise coming from the internal speaker.... My new G5 sounds like a *Geiger counter. it comes and goes according to activity. It doesn*t seem to affect the audio out port but still persists. Even when I have a head phone jack plugged in it still make the sound. Of course it shouldn*t as the internal speaker should be disabled by the head phone jack. One theory is that the internal speaker is picking up noise from the power supply. It is very annoying. Pass it on.
-Russell
Of course Apple has never heard of this problem.
(He later wrote)
I installed Chud tools but it didn't help. I could find no difference with or without. I also reinstalled the OS system to my liking, not the default setup it came configured with. It seems my internal speaker sounds sorta like a Geiger counter. A clicking sorta noise. I may have to unhook the internal speaker from the motherboard or wait till 10.3 comes out. I think it may be a problem with close proximity of the power supply wiring to the internal speaker. But then what do I know... I've been an Electrical Engineer for 20 years working for NASA...
When I plug in my headphones through the front jack it "should" disable the internal speaker from playing any audio. mp3's etc... And it does just that, as it should. I do not hear any of the "Geiger counter noise through the audio out the front headphones jack. In fact the audio out the front jack sounds great through my headphones. But I can still hear the "Geiger counter noise" through the internal speaker. This is why I think it making noise via induction. I'm 95% sure that the noise isn't coming through an audio line signal. I would think that the power supplies would be the same through out all 3 G5 models. Odd that it only affects the dual G5. "

I can't remember if any single G5 owner reported this same problem with the internal speaker. (The Dual G5 has a higher wattage power supply than the other models and is drawing more power when it slews in and out of Nap mode, which may make this more noticeable on Dual G5 systems.)

(Not a G5 owner report - but posting as a FYI)

" I have those noises but on my G4, TiBook 1Ghz. I can narrow them down to when my web browser is transmitting data (for instance uploading an attachment or placing files on a server from FTP. I have no idea where this comes from and I have never seen similar behavior on earlier macs. It is not from the speakers either, this is from some other part inside the TiBook (my guess is somewhere just under the "p" key, or thereabout. Strange but true...
Fredrik "

There were some past reports since OS X was first released of audio noise when using Airport (most noticeable with large/high speed downloads) but not sure if that was fixed in a later OS/Airport update. (I haven't checked for it in months.)

Another non-G5 owner wrote about audio noise:

" My brand new (2 days old) iBook 900mhz is doing the exact same thing. I didn't notice it until after I did a system update, so I don't know if it always did that or its new, it seems to actually be coming from the right speaker and not the computer itself, but I have the same barely audible clicks.
James T. "

Didn't say if using Airport (wifi) for networking.