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Updated July 10, 2007
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iMac G5 - Too Noisy? - ScienceMan Investigation
Finally, some good news!
The latest revisions of the iMac G5, that is, the third generation model and the Intel Core Duo model, seem to be wonderfully free of fan buzzing noises.
Many users have reported that their 3rd generations machines are quiet, and ScienceMan can personally attest to this. I've been lucky enough to use a 3rd generation machine, and they are near-silent, with no hint of buzzing. This goes for heavy processor loads as well, when the fan ramps up, it is still very quiet.
Apple hit a home run with the new design for several reasons, but with respect to the fan, the success of the 3rd generation machines is due to rearranging the fans so that air is drawn into the machine at the centre, instead of the botttom:
On a side note, the relocation of the ports horizontally near the bottom makes a lot of sense too, as opposed to the vertical arrangement in the previous models.
It feels great to be able to finally say - go out and buy yourself an iMac! Your eyes AND ears will love it.
But what about the poor suckers with buzzing generation 1 and 2 machines? ScienceMan has updated the Fan Modification Forum with more user reports and ideas.
The iMac G5 story continues to get more interesting with the Apple's announcement of the iMac G5 Repair Extension Program for Video and Power Issues. This program covers 17" and 20" iMacs within specific serial number ranges, and readers have already reported that both rev. A and rev. B machines fall into the serial number range. ScienceMan can confirm this, his rev.B machine falls into the serial number range as well (oh goody!)
Apple has not been specific as exactly what components are covered under the extension repair (2 years), but it's probably safe to say that the defective components are the power supply and logic board capacitors (see table below).
OK, let's get straight to the bad news - for those of you hoping that fan noise would be covered under this warranty service, forget it. Note the specificity of the title of the extension program! Fan noise continues to be an issue for many users, and judging by ScienceMan's email, it seems that the noisy fans (primarily on, but not exclusive to, rev. A machines) can get worse over time.
There have been some hints that Apple will address this fan problem, it just seems to be a matter of how sympathetic the particular service provider is, or how nasty the noise is (but that's oh so subjective, isn't it?) What's even more interesting is that there seems to be an undetermined differences in motherboard/case design in these iMac G5s. Some users have reported being able to access and remove the processor fan and housing without having to lift out the entire midplane.
This page is becoming rather lengthy, so please visit ScienceMan's iMac G5 Fan Modification Forum for more details on users tinkering with their fans, and emails regarding experiences fan noise.
June 23 2005 Update
A quick and thankfully uneventful update regarding the revision 2 - 18" G5 iMac. This machine has been performing spectacularly for a month now. No problems whatsoever, and it is shocking how quiet this unit is compared to the revision 1 machine (see below).
Even under heavy processor loads, the fan noise in this particular revision 2 machine is delightfully quiet. Sure, you can hear the processor fan ramp up under heavy loads, but it is just soft rushing air noise, not like the incredibly annoying "remote controlled airplane" noise from the revision 1 unit.
After having read forum postings regarding leaking and bulging capacitors - I have been checking periodically and can report no such problems. All capacitors look intact and normal. Both machines, revision 1 and 2, perform excellently - it's just that one's noisy, and one is not!
So what to make of all this so far? It's hard to draw definitive conclusions - but based on the collective evidence presented by the online Mac community (and my own meagre testing), there seems to be three major issues regarding the iMac G5 model:
Issue
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Thoughts and Recommendations
(Please keep in mind I AM NOT an Apple technician, I'm not even particularly intelligent! These are not official recommendations, just ScienceMan's opinions!) |
Fan Noise
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From my own testing with iMac G5 17" models, it would seem to me that Apple has made improvements in the revision 2 model that make it quieter.
I went through a rigorous complaint process, going so far as to demonstrating the noise in the revision 1 model at an Apple dealership. The response was that the noise is within specifications. Good gravy!
With something as subjective as noise - my recommendation is to be persistent with your complaints if you find the noise of your machine intolerable.
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Failing, Leaking Capacitors and Overheating
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Since I don't have direct experience with this issue - so I won't be so arrogant as to comment on it.
I recommend the excellent Macintouch G5 forum to get more information on this unfortunate problem.
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Power Supply Failures
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Again, I don't have direct experience with this, but I will comment on this one, only because I have talked directly with two Apple Certified Technicians regarding this issue.
This issue seems to be much more prevalent with iMac G5 20" model, and can manifest in many ways. This issue can cause screen anomalies, popping noises, burning smells, system freezes, and complete catastrophic failure of the unit.
The bottom line is that your iMac G5 should perform flawlessly - if you are having problems that lead you to suspect a power supply problem, you should contact Apple service.
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May 30 2005 Update
A couple of months ago ScienceMan posted a movie illustrating the obnoxious sound made by an iMac G5 (17 inch model, 1.6 GHz). You can still see it on this page. As for the loud sound, no resolution to the problem was ever reached - on a couple of occasions the buzzing iMac was brought into Apple authorized service centres; their opinion was that the sound was normal. Uh yeah, right! The iMac G5 (first revision) is an incredible machine in all other respects - it has functioned flawlessly since purchase - the only problem has been that darn remote-controlled airplane noise it makes!
When ScienceMan got his hands on a new, second revision iMac G5 (17 inch model, 1.8 GHz), he couldn't wait to do some comparisons with the old model. First. let's crack the case on these models side-by-side:
Internals
iMac G5 original model on left - iMac revision 2 on right
click image to enlarge
At first glance the models look very similar - but if you look closely in the area of the Airport card, you will see something very interesting in new model - there is no Airport card! Well, at least not a removable one. Apple has included Airport and Bluetooth standard on all new iMac G5 model (great idea!) - so obviously they have streamlined production and minimized the components as much as possible. I suppose this means you can't take the Airport card from a new G5 iMac and put it into another Apple model - but who cares? Here's a closer look at that area:
Airport Card
iMac G5 original model on left - iMac revision 2 on right
click images to enlarge
 
Hmmm... the next thing you notice is the difference in the system and hard drive fans. You have to wonder why the fan design has changed - Apple getting lots of noise complaints, you think?
System Fan
iMac G5 original model on left - iMac revision 2 on right
click images to enlarge
 
Hard Drive Fan
iMac G5 original model on left - iMac revision 2 on right
click images to enlarge
 
What about the processor fan - the major culprit in the noise production (scroll down this page to hear a movie of the hideous noise). You have to pull the midplane to get the cover off the processor fan, and I haven't been in the mood to do that. But Apple must have made a significant change to the processor fan - it is MUCH quieter now, and God bless Apple, the remote-controlled airplane sound is gone! No more buzzing!
The new model iMac G5 still has a processor can that ramps up its speed when under heavy processor load - but the fan noise is just that - gentle fan noise - as it should be.
In general use, I can report the new iMac G5 model has been pure pleasure. As noted above, the noise of the machine is now more than reasonable, and the performance is superb.
Just one more thing - I noticed one more strange difference between the two models. If you look carefully at the new revision - at the bottom of the case in the grille there is a small bubble, with what looks a photocell inside, but it really could be anything. Is this some sort of feature aimed at a future remote control???
The first revision iMac DOES NOT have this strange bubble. Does anybody know what it is?
UPDATE! MYSTERY SOLVED!
Thanks very much to the many Mac aficionados who emailed ScienceMan to let him know that the mystery bubble is an ambient light sensor - it dims the flashing sleep indicator light when in the dark, presumably so as to let all us G5 iMac users sleep in peace! More info on the ambient light sensor is on the bottom right hand corner of this page.
The recent release of Apple's mac mini has really stolen the thunder from their iMac model. Many reviewers have noted that after buying an Apple display and accessories, the mini will set you back about the same amount as an iMac will, and you will have a less-capable, less-upgradable computer! But that's not the point - the mac mini is obviously meant as a second computer that will hopefully end up next to a lot of home PCs (showing "dark-side" users the light). Kudos to Apple for a great little machine.
Both machines are getting rave reviews, except for a couple of small issues. In regard to mac mini, there is little point offering a machine with 256 MB ram. Why not make 512 MB standard? 256 MB is not enough, simple as that, 'nuff said. The other issue is a little touchier - iMac G5 fan noise. Apple has already removed a forum thread from customers that have complained about this issue. Why? Is there a problem, or are Apple users just fussy about noise?
Well, ScienceMan has a G5 iMac as a second machine, and I regretfully must confirm the problem. To understand the issue, it's first necessary to look inside the case:
 The iMac g5 is equipped with 3 fans. There is a small one meant for hard drive cooling (A in the diagram).
There is another just below it, this could be called the "case" fan or "system" fan (B in the diagram) meant to exhaust heat out of the vent at the top of the iMac.
Both of these fans are very quiet, and make soft air movement sound when operating. With the case closed, they make barely noticeable sound during normal operations. Even when the system is taxed, such as with a processor intensive game, the air movement noise is not bothersome at all.
The culprit is the last fan, which is encased is a rectangular case and is ducted directly to the G5 processor (C in the diagram). This fan is meant to draw air into the system to pass over the heat sink of the processor, where it can then pass out the vent at the top of the processor housing. There have been many descriptions on the web of the sound of this fan, but I think the most apt is "remote-control airplane". It seems that in some G5 iMac systems, this fan generates a gentle whir, but in other systems, it can be an intolerable buzz that only goes away when the system is put to sleep (and even that doesn't help in some cases).
Time to judge for yourself! Turn up the volume on your computer, and then start the following movie. ScienceMan used a microphone to illustrate the difference between the fan noises:
What do you think? With a microphone next to fan A, the hard drive noise is also noticeable, but besides that it is just air noise. Fan B, although larger, generates only soft wind noise, and at a lower pitch than fan A. But fan C sounds, well, it sounds like a buzzing remote control airplane!
Granted, this is hardly a scientific test. It should be noted that the processor is set to "auto", with Safari, iTunes, Recipe Manager (hey, no laughing!) and a couple of other applications running. Some users have had luck reducing fan noise by adjusting processor settings in the Energy Saver preferences, but I have found these settings make little difference. Also, the fan noise from C is MUCH WORSE when the processor is heavily taxed, such as while playing a game.
Another note is that the noise never completely subsides. While many users report their systems are near silent during normal operation (word pro, surfing the web), ScienceMan's iMac is only silent when asleep. When operating, the buzz is always there. With no apps running, it is a low-grade buzz, but just starting a single app such as Safari begins to whip up the buzzing.
Conclusion? It would be nice to easily take the cover off to be able to see the culprit processor fan, but unfortunately the whole "midplane" assembly (guts) of the computer must be lifted in order to remove the cover. Is there something rubbing in there? Is it just a poor quality fan? Is it poorly mounted? Who knows - but in my humble opinion this fan need not be any noisier than the other fans in the system. Why use a fan with an annoying buzz? It would be really nice to be a fly on the wall during Apple engineering meetings! ScienceMan has to come to the conclusion that Apple dropped the ball on this one, and as a result has set a very annoying undertone to an otherwise fantastic piece of engineering. If Apple was customer-savvy on this one, they would get themselves some quiet fans and design a kit for processor fan replacement - then start sending those suckers out!
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