Power Supply noise

Hi,
I bought a new macbook 2 weeks ago and since this morning the power supply makes some noises.... Is it OK? Why? My ols PowerBook 12" s power supply didn t do it...
Thanks

My new macbooks is wonderful and I'm very excited about it, BUT the adapter sounds terrible and loud - a sizzling sound as others have described.
I called Apple immediately and they escalated me to a product specialist who said they are 'capturing' all adapters with these sounds and that he'll overnight me a new one. I think everybody who has this problem should have it replaced because it doesn't sound good. Any Apple genius that says it's within specifications and ignores it is also ignoring Apple's capture policy on these things. We don't know what the problem is and it's better to err on the side of caution than to risk a fire.
In fact, the Apple specialist I talked to said it's better not to use the adapter for now. I trust his judgement on this.

Similar Messages

My Macbook Pro with Remakes funny noise when connected to power supply cable and no other response. The best description of the sound I can give is the buz the computer makes on startup. Sound goes on and off while connected

I am new to the Macbook community. I own this Macbook since 10/2012.
My Macbook Pro 15 with Retina Display suddenly totally stopped responding. No display, no activity on keyboard. When I connect power supply cable, the Mac makes a noise as if it is starting up, but this lasts a second and this sound comes and goes the whole time the power cable is connected.
Any advice?
Thanks!

Reset the SMC and the NVRAM:
http://support.apple.com/en-us/HT201295
http://support.apple.com/en-us/HT204063
The try a safe boot:
http://support.apple.com/en-us/HT201262
Any change?
Ciao.

Mac Pro 8-core Power Supply Making Humming Noise That Comes And Goes

This is in reference to a Mac Pro 3,1 8-core purchased around Feb 2008.
Lately, I've noticed a strange noise coming from my power supply that sounds like the noise a refrigerator radiator makes. It's a humming noise that rapidly comes and goes, constantly.
The power supply fan speed is running at 599rpm
I'm not sure if the problem could've been caused by adding additional ram (12GB, OWC) or an additional HDD (3rd HDD, WD), but I didn't really notice the noise until after adding these components.
What could be the cause of this problem? What are my repair options if necessary (without Apple Care)?
Thanks in advance.

I know for a fact it is not any of my hard drives because the noise is becoming more frequent no matter what hard drive I use, I actually have a 1.5tb, a 1tb, two 500gb and two 320gb drives, I have set an appointment to take my system in and have it tested, it is starting to crash 5-6 times a day. I can not get a lot of work done with this annoying spinning noise and the shutting down. Thank god for my Apple care, and I have visited various forums that lead me to believe its the power supply going out, with the symptoms it is having. This article and others like it explain what to look for when a power supply is going bad.
http://www.smartcomputing.com/editorial/article.asp?article=articles/archive/r07 04/24r04/24r04.asp

Fan noise when I Target Disk Mode - power supply or 500 GB drive, or RAM?

I have a Revision B iMac G5 which falls squarely in the power supply replacement program and has had the power supply replaced twice. I'm wondering if my extra RAM, or larger hard drive could be to blame for the fan speeds upramping at random during normal operation, and always when I Target Disk Mode the machine. I have a Western Digital WDC WD5000KS-00MNB0
and two 1 GB RAM modules with the following spec PC3200U-30330.
Before I try to pin down the cause one by one, has anyone noticed whether there are 500 GB drives on these Macs which will not up the fan speeds? Has anyone noticed whether target disk mode on these models will not increase the fan speeds when RAM is upgraded to 2 GB?

I have the same iMac as yours. Changed the original 80 gig hdd to a 250 gig. Both drives are seagate barracudas. I also upgraded the memory to 2gigs. The fan noise was terrible.
6 months later a ram module gives up the ghost. I originally thought hard drive, so purchased a Western digital 500 gig WDC WD5000AACS-00ZUB0. (The green power series).
http://www.wdc.com/en/products/Products.asp?DriveID=338
Fans very quite. still waiting for the replacement ram module;
to see if extra ram will increase fan noise
.

My PH m7160n Desktop PC the power supply make high noise no signal to the monitor

my PH Media Center m7160n desktop PC the power supply make loud noise and no signal to the monitor I already replace the power supply but still the same, Thanks
Davilea

Hello @davilea,
I understand that you are getting a loud noise from your computer and a 'No Signal' message on your HP Media Center m7160n Desktop PC's monitor. As you have already replaced the power supply I will provide you with the HP Support document: Flat Panel Monitor Displays Message about No Signal, Signal out of Range, Sleep, or Power Save, which should help you resolve the 'No Signal' message.
Please re-post if you require additional support. Thank you for posting on the HP Forums. Have a great day!
Please click the "Thumbs Up" on the bottom right of this post to say thank you if you appreciate the support I provide!
Also be sure to mark my post as “Accept as Solution" if you feel my post solved your issue, it will help others who face the same challenge find the same solution.
Dunidar
I work on behalf of HP
Find out a bit more about me by checking out my profile!
"Customers don’t expect you to be perfect. They do expect you to fix things when they go wrong." ~ Donald Porter

Mac Pro Power Supply making noise (even when turned off)

Hi everyone,
My Mac Pro Early 2008 (Dual quad core 2,8) began to make noise a while ago and it drives me mad.
The sound is (100% sure) coming from the Power Supply. The sound is not mechanical, but electrical, like an oscillator crackle sort of.
First I thought it was the PSU itself, so I had it replaced with a new one, but that did not change the situation.
The (new) PSU makes excactly the same noise, even when my computer is turned off (but still connected to the power socket in the wall).
I've eliminated all possible factors that could create an interference (other electrical devices). I even completely switched off the power of my office, except for one power socket; the one I used to test the Mac. As soon as I connected the Mac, as soon the noise came back. So, it's got to be inside the Mac.
So my question is: if it's not the PSU, nor the power of my office, what could it be?
PS: I've tried a UPS too... but that did not change a bit.
Thanks for your suggestions!

Hey
I appreciate the attention and help from you guys. I installed hardware monitor and this is what tells me:
Ambient Air 22
CPU A Heatsink 28
CPU B Heatsink 29
CPU Core 1 27
CPU Core 2 30
CPU Core 3 29
CPU Core 4 27
Expansion Slots 32
Hard Drive Bay 1 30
Hard Drive Bay 2 25
Hard Drive Bay 3 24
Hard Drive Bay 4 24
Memory Bank A Point 1 38
Memory Bank A Point 2 44
Memory Bank A Point 3 44
Memory Bank B Point 1 37
Memory Bank B Point 2 44
Memory Bank B Point 3 48
Memory Module A1 65
Memory Module A2 65
Memory Module A3 62
Memory Module A4 54
Memory Module B1 69
Memory Module B2 65
Memory Module B3 59
Memory Module B4 57
Northbridge Heat Sink 63
SMART Disk Maxtor 6V300F0 (V60E4NQG) 41
SMART Disk ST3500630AS P (9QG0H24P) 31
Do you have any suggestions? is it safe to find a program to regulate the fan of the power supply down or can this damage the system?

Power supply fan dead - help? (400mhz AGP G4)

Hello!
Unfortunately, my PowerMac G4, a 400mhz, AGP Sawtooth model, has a dead fan.
Over the last few weeks, I've noticed that my G4 has been running quite hot. I figured it was due to the hot dorm room that it's being used in. Then, I noticed that when it booted up, it would occasionally make a vibrating, or rattling noise - I figured the fan was wobbling. Since air was comming out of the fan opening at the top, I didn't worry about it.
Today, I used the "Temperature Monitor" widget to check the temperature of my SMART Hard drive (the G4 itself is not sensed). It was 133 degrees!!! This is the bay on the back-right, just under the CPU fan. I looked at the fan again - not much airflow. I pulled out a flashlight and pointed it in, and the Fan that's inside the power supply unit is dead.
So, how can I fix it? It's far far too hot, so it's not usable until I can cool it off. The first idea I had was to take a particularly powerful desk fan, and make a paper "tube" that connects both to the G4 and back of the fan - so it'll pull the hot air out. Needless to say, this is not a good log-term plan as it's easy to fall apart and will have leaks, but it works for now. I realize you can buy power supplies, but for ~$100, it's far too much for the old G4.
Second idea: The fan is inside the "non-user servicable" power supply, but it's also next to the back of the G4 - right inside what appears to be a panel that holds the power supply in. At the very least, I'd like to make sure that the cable is attached and not loose, but I have to open the back. Is that possible or safe? If so, can I replace the fan?
My third idea was to attach an extra fan to the inside of the G4, on the outside of the power supply - pushing in. Unfortunately, the IDE cable from the DVD drive is in the way, and there's not much room for a fan. Plus, there's no fan power supply. Is it possible to convert an ATA power plug (there are 7!) to a fan-power supply? I'd require a small circuit and a lot of resistors, obviously! If so, what would I need to do to convert it?
Thanks a bunch,
-Dan
15" 1.67 Powerbook G4 (Jan 2005), 400 mhz AGP Sawtooth G4 Mac OS X (10.4.8) 4G Clickwheel and 5G Vid iPods, 2G iPod shuffle

Thanks!
Interesting, this "Piggy back power adapter" will allow me to plug the fan into one of the ATA/IDE cables? Or do you mean the extra port on the power supply? (it has one plug for the outlet>G4, then another to support something like a monitor or similar) The G4 has a DVD burner, but no ZIP drive, so this is quite do-able if it uses the ATA power.
When you say "lower rear", do you mean at the bottom? Below the power supply, to the right of the PCI slots? If so, this is the inflow for the CPU fan! I can understand mounting it outside the current outflow-vent for the dead power supply fan, although I'm not sure the best way to proceed with attaching the fan.
Another question: what tools and supplies will I need? I may need to remove the plastic cover on the back of the G4 - the one that is outside the power supply - as there's a gap between the gray plastic and metal chassis that lets air from outside the machine come in. The screws for this cover use a funky, hexagonal screwdriver. If I need to take this cover off, what kind of screwdriver will I need? Also, should the fan not include screws/etc, what's the best method to attach it? Glue?
Secondly, to cut a hole in the G4, will I need some variety of drill? I don't have one, so i'll have to borrow one... Since there's nothing in the ZIP slot, I can run a cable out through here (assuming it's long enough), and make a new bezel to keep the airflow inside intact.
Ah! One other (somewhat related) question: my USB 2 card includes a power adapter, for use when several un-powered devices (flash drives) are attached. It works just fine with a flash drive and a small media reader, but it's slow to sense the drives - I think it's low on power. Unfortunately, this power plug uses the same variety of plug as the floppy disk drives found on many win-boxes - of which the G4 possesses none. Is there an adapter/cable for this purpose?
Thanks, this is a HUGE help, I appreciate it.
-Dan

UPS Causing Disturbance to Mac Pro Power Supply

I have been doing a lot of work on upgrading two Mac Pro's over the last few days. I have one attached to an APC UPS 1300VA 780W rated. Normally this Mac Pro is under my desk, so I do not here it. During the process of one of the upgrades I had the Mac Pro sitting right in front of me on my desk. As soon as I powered it up, I could hear this disturbing "hum" or "buzz" coming from the power supply of the Mac Pro. However the Mac Pro seemed to operate fine.
I decided to unplug the Mac Pro from the APC UPS and into a regular Tripp-Lite wall surege protector with no UPS. The noise was significantly reduced. Therefore my question to you is:
1. Do you think the fact that the APC is creating the problem or introducing a different signal (maybe not true Sine Wave) than what is required by the Mac Pro?
2. For those that have a newer Nehalem Mac Pro and they have access to the back, how would you rate the "hum"? Is it what you would expect? Now that I have it off the APC UPS, it seems more normal (it is audible, but only with my ear close to it).
3. How well are the power supply units in the Mac Pro designed? Enough to handle immediate loss of power? What about cleaning the power coming in? Sometime the voltage drop across my AC outlet is 110V to 120 V.
Mike

RS? XS? something other than those? The linked discussion OP had an XS and went to SMART unit. Before I bought CyberPower to replace one of my two 1500VAs (one XS and other RS) I decided to ditch APC this go around. And, glad I did. Quiet, green, stand-by mode.
The 2008 had bad inrush current, and ever since the G5 Quad with 1kw PSU people have been looking for the best UPS.
One article talked about PSU efficiency, and apparantly Apple's didn't match the 85+.

The Power Supply Fan is still working, but does not appear to respond to increased loads, and its speed cannot be increased using SMCFanControl. Any suggestions?

Hi all - My mac pro 1,1 has an enigmatic problem. It's quad-core, 3Ghz, running OS X 10.7.5. The problem began some months back, when running HD video conferences, HD streaming videos and some other graphics-moderate (I won't say intense) uses, such as slide shows in Just Looking. My machine has an ATY, RadeonX1900 card and 2 monitors - both Apple displays, one being 30 inch 2560x1600, the other being 24 inch 1920x1200.
When I start those types of graphics-moderate apps, after about 5 minutes, something would crash (the monitors making a noise as it did) and the displays would both go black. The power did not appear to be fully cut off from the monitors. I think that the underlying applications, however, did not crash. So, I could still hear and speak to people during video conferences, and I could hear the sound tracks of videos.
Attempts to restart the computer and get the monitors back did not immediately work to undo the problem, if done straight away. The only way to correct the problem (so as to have the monitors work) was to wait for a few minutes and then restart.
After a lot of puzzled looking at console logs (and I confess that I am not an expert), I ran into a blank.
But, because of the timing of the crashes (after ~5minutes use) and restarts (after some minutes wait), I reasoned that the problem might be temperature related.
Once on that path of thought, I found this article:
http://worldtv.com/blog/guides_tutorials/fixing_an_overheating_mac_pro_no_expens e_required.php
I installed both Temperature Monitor and SMCFanControl. And I experimented, and got interesting results:
Now to the puzzling bit: SMCFanControl shows that the speed of the Power Supply Fan doesn't vary much, even if I use SMCFanControl to ramp fan speeds right up. All of the other fans react to SMCFanControl, going up to and above 2500rpm when commanded. But the Power Supply Fan does not. Having watched it for a few days now, the Power Supply Fan, according to AFCFanControl, never varies outside of a range from about 600-640 rpm, regardless of what I do with AFCFanControl.
Also (and not surprisingly), whenever the graphics-moderate apps run, when I ramp all the fan speeds up using SMCFanControl, Temperature Monitor shows that the all of the temperatures within the machine plummet, except in the power supply locations. Power Supply Location 2 is the worst affected. Because the Power Supply Fan does not react as the other fans do, the "crashes" still occur.
I could post some screen shots of the read outs of SMCFanControl and Temperature Monitor, although I think I have covered the key points in this post.
It seems that the Power Supply Fan is still working, but does not respond to increased loads.
Instinctively, I'm worried that if that's right, it might be a hard problem to fix. Any suggestions? Help! I would really appreciate them!
Cheers
P

Thanks for your response Grant. I had already read about, and I think excluded, dust in graphics card/fan/assembly as a cause. The entire inside of the computer, including the graphics card/fan/assembly, is as clean as a whistle. It looks clean. I've cleaned the dust out every now and then (including a few days ago). Also, my undersanding (derived from the article, linked in my first post) is that I might expect to see high temperatures in the Northbridge and memory module B if the graphics card was overheating. According to Temperature Monitor, however, locations do not increase in temperature when I run the relevant apps. Finally, the graphics card/assembly does not feel too hot to touch.
It is strange that SMCFanControl lists the Power Supply Fan as being software controllable, if that fan is not. Still, your comments are consistent with my observations, as the fan simply does not respond to software control.
There are two upsides: First, I've something of a work-around. I've worked out what temperature must be achieved in Power Supply Location 2 for a crash to occur, and I can watch that location in Temperature Monitor, terminating the process before that treshold is reached. Of course, that's not ideal. Second, ramping all the other fans up does significantly delay the onset of the problem, and makes recovery time much quicker.
Is there any donwside to peridically ramping up the other fans when running the relevant apps? Given that it causes all of the other locations to cool significantly, could this lessesn the life expecancy of the mahcine? (I don't want to run the fans up all the time - that's like sitting next to a jet ready for take off!)
Also, a correction to my first post: Yesterday, with all the other fans running on full and running an HD streaming video, the Power Supply Fan did, eventually, slowly, come up to ~740rpm, which is much higher than the ~640rpm maximum I had previously seen, and this may have aided delaying the onset of the problem.
I'm not sure where this leaves me? The problem might now be able managed. Well, sort-of. But it's not eliminated.

Noisy power supply when running of UPS?... follow up post.

Ned/The hatter your input here would be most appreciated along with anyone else using a UPS with your mac pro. Please read on...
Having just concluded a rather detailed any lengthy post over in the power mac g5 forum with regards to loud buzzing noise from the power supply running of battery backup.
I recemmend reviewing the link below for the full and i think interesting read...
Linked here: http://discussions.apple.com/thread.jspa?threadID=665537&tstart=0
To sum it up it concluded that my model of UPS (Belkin) produces a simulated sine wave. I am unsure of technicals here, but this then makes the power supply in powermac G5's make a nasty electrical noise as the unit works to sort it out. What is ideal is a pure sine wave i understand.
The reason for my post was that i was concerned the noise was a sign of harm being done to my mac. No one has said either way yet that this noise is either just a nuisance and it something thats got to be lived or that its actually harming my machine.
Anyhow it turns out that the RS series from APC also makes the G5 powermac make a noise. And i am aware that Ned along with some others use the APC RS series with there mac pro's. What i am looking to find out is... Do you have a noise from your power supplys when running on battery backup with your new shiney mac pro's?
The APC smart ups series however does not make the powermac G5 make a noise this has been confirmed by several users. I guess this is because these models produce pure wave sine.
As you can see this has all got very complicated and over my head.
The reason for me coming into this forum and asking about noisy power supplys when using certain UPS is because shortly i will be switching to a Mac pro. And if the power supplys in these are different and dont make a noise when running under battery with certain APC Rs's and the new Dual form belkin units then i wont return my current belkin model in exchange for a APC smart ups. I will just live it for a short time whilst i own my G5 and just hope it wont do any damage if and when we have a power outage.
Thank you to anyone that can guide or assist me with this dilemma. Cheers Pob

Pobster,
Switching power supplies (such as those used in computers) do not require a "pure" analog sine wave input; they are more than capable of running on PWM/stepped sine wave input. The noise from the power supply when running on power from a PWM output UPS does not indicate that damage is being done to your machine; it's a harmless side effect.
Some equipment will be damaged if powered via PWM input; items with compressors (refrigerators, air conditioners) definitely fall into this category, as well as some medical equipment and telecom equipment.
I live in an area with notoriously dirty power; a UPS is critical in my case (I'd argue that it is critical in any case, however). I've ran my equipment on UPSs for many years, and the price has dropped significantly. I've got one APC SmartUPS with pure sine wave output which was purchased for me by a client, but most of my equipment is running on UPS with PWM output. It's not uncommon for me to have 20-30 power events in a given day - most of them transient voltage drops or spikes; I've still got an old Sun Sparc 10 file server that's still chugging along.
A couple of interesting articles for your perusal:
http://www.macosxhints.com/article.php?story=20051009043816537
http://en.wikipedia.org/wiki/Pulse-width_modulation
A quick google will turn up lots more information on the topic. APC used to have a white paper on their site which talked about this very topic.
Most manufacturers provide connected equipment insurance - tripp lite, for example, provides $250,000(US) coverage. I've never known anyone who actually needed to use this coverage - I certainly haven't .
In brief: A UPS with PWM output will not harm your computer; switching power supplies are more than capable of handling this. If the noise bothers you, look for a UPS with "pure sine wave" output - you will pay more for this feature; it's an aesthetic choice in this case.

2008 iMac 8,1 still won't power up after replacing power supply

A few days ago my iMac powered-ON as usual at 8AM and was working normally, I checked email and left for a meeting. When I returned 30 minutes later my office had a slight odor of hot bakelite and the screen was dark, instead of displaying the screen saver. Thinking the power may have blinked, I pushed the start button on the back and nothing happened, tried several more times, then depressing and holding, still nothing - absolutely lifeless.
Presumed it was probably the power supply, so took it into the Genius Bar and my suspicion was confirmed; they checked the LEDs and advised that the power supply was mostly bad. Despite the hassle, the solution seemed simple enough: replace the power supply and I'd be back in business. That proved to be wrong!
Bought a new (NIB) power supply from a reputable dealer and carefully disassembled/reassembled the iMac feeling ever so confident that I'd hear the chime and fan whir when I depressed the ON/OFF Button. To my total disbelief nothing has changed! Its still dark and lifeless as before. Not discounting a theoretical chance that both power supplies could be bad I'm puzzled what to do next and where to look. Obviously, there isn't much in line ahead of the power supply, but given the fact there is no fan noise and no glimmer on the display, I can't fathom it could be anything other than something between the power cord and the power supply.
What could have caused the hot bakelite smell? The original power supply had NO bakelite odor and no burned chips, traces, scorched transformer windings or cooked capacitors. That had surprised me, so sniffed around the motherboard/backplane and detected a slight bakelite odor at or near the hard drive; I haven't cracked the case yet to examine the HDD - but, even if it were dead, I'd still hear the chime and fan, and maybe see at least a slight glow on the display, right?
And so, I'm calling on all you "pros from Dover" for some insights, wisdom and pointers to help me diagnose the problem and get the thing fixed. Your thoughts?
Thanks, much, compadres. AK

My assumption is the same as KT’s, the logic board fried. If the logic board is functional, even if the hard drive is dead, it should power on and perform the POST. Since it isn’t my advice is the same as KT’s - hope you don’t need Snow Leopard to run some older program(s).

How can I replace the power supply IN the time capsule

I have a TimeCapsule that has a bad powersupply. I have opened the timecapsule to confirm this. Has anyone done this before? If so, where did the power supply come from? Cost? I took this to the Apple Igneous bar and they said there is nothing that can be done about it.They said it couldn't even be opened, but simply peeling the rubber bottom off and unscrewing a number of tiny screws and that's it. The 1 TB drive is LOOSE in there. That was a bit of a surprise. I had thought that the issue was the drive itself was bad. I had hoped that if I removed that the AP part would at least work, but after opening it up and firing it up I could hear that the power supply was buzzing thus the conclusion it was the issue.
I am going to put the SATA drive in a reader to see that it is indeed ok. If that checks out, then I know for certain it is the power supply, but I don't know what to use as a sub since the unit needs both 12V and 5V. I'd just as soon find a good supply and use that. Any help would be appreciated.
Thanks,
John A Kostelac

What version is your TC.. A1xxx from the rubber foot?
Power supplies are not available from apple. They do not consider it repairable. It is a sealed consumable.
Power supplies are available from ebay.. simply type time capsule power supply into search.
This is absolutely standard issue that has been ongoing for ages and ages.
See https://sites.google.com/site/lapastenague/a-deconstruction-of-routers-and-modem s/apple-time-capsule-repair
For a multitude of ways to fix it.
The 1 TB drive is LOOSE in there.
No, it is not loose, it has rubber mounts with pins in the bottom base plate. You cannot see the mount points with the base off. This is standard hdd mount for low noise and vibration.
I had thought that the issue was the drive itself was bad.
Drives seldom are the problem. The Gen2 WD black has been less than great though.. and later spinpoint in Gen3 not so good.
Apple Igneous bar

Where can I buy a replacement power supply (model VP-09500018-000) for my 1st generation Time Capsule?

My 1st Time Capsule no longer powers on! It was making noises for a while before it would no longer keep power / turn on! I have taken the time capsule apart and could easily replace the power supply if I knew where to buy it Can anyone lead me in the right direction?
Thank you!

Apple do not supply it as a part.
You can repair the existing supply.
https://sites.google.com/site/lapastenague/a-deconstruction-of-routers-and-modem s/apple-time-capsule-repair/apple-time-capsule-repair-type2
Plenty of people sell the caps set on ebay. Cheaper if you have a good electronics store handy but they need to be top quality low esr capacitors.
Substitute a different kind of power supply.
I definitely believe in using external power supply for this job. This is my own website so disclaimer.
https://sites.google.com/site/lapastenague/time-capsule-power-supply-repair-kits
Or some original type are available on ebay. Just search for "Time Capsule power supply"
Or look at what a whole second hand TC will cost you.. a Gen3 or Gen4 can be a better proposition than repairing a dead Gen1.
You can also do a half repair.. By that I mean you only need one voltage to run the TC.. a single 5v 3A power supply plugged into the TC board socket or soldered directly in.. will give you an airport extreme Gen2 for $10. Plug the hard drive in by USB.. or use a bit of careful hacking and use a SATA cable to the post on the board and use a 2TB or even 3TB esata case.
You can also still buy a Cisco dual voltage supply on ebay.. but the wiring of it is a bit rough.
https://sites.google.com/site/lapastenague/a-deconstruction-of-routers-and-modem s/apple-time-capsule-repair/cisco-adp-30rb-4pin-molex

IMac G5 won't start up - logic board or power supply?

My oldest son killed my iMac G5. Apparently he'd taken to sneaking downstairs in the middle of the night and watching videos on YouTube. One night, during his viewing session, the iMac threw up a kernel panic and the fan came on. My son tried to turn off the iMac but couldn't find the switch. So *he went to bed and left the iMac with the fan on full-blast.* When I came downstairs to go to work, 6 hours later, I turned off the machine, waited for a minute or so, and then attempted to turn it on.
The iMac is stone dead. Will not turn on.
I'm deathly afraid the logic board is cooked. Those things are damned expensive. I held off on doing anything for a while, but then I was talking offhand with a Genius at a local Apple store. He said it might be as simple as a power supply. Which would be great - $125 is a lot cheaper than $800, and I could do this repair myself. But I don't want to sink $125 into the machine unless I have a pretty good idea that this will, in fact, fix it.
Anyone else had this problem? Did it turn out to be the logic board, or the power supply, or something else entirely?

First off, the kid is grounded - second, which model do you have? Have you tried resetting the SMU? Resetting the SMU can resolve some computer issues such as not starting up, not displaying video, sleep issues, fan noise issues, and so on. If your computer still exhibits these types of issues even after you've restarted the computer, try resetting the SMU. To reset the SMU on one of these iMacs:
1. Turn off the computer by choosing Shut Down from the Apple menu, or by holding the power button until the computer turns off.
2. Unplug all cables from the computer, including the power cord.
3. Wait 10 seconds.
4. Plug in the power cord while simultaneously pressing and holding the power button on the back of the computer.
5. Let go of the power button.
6. Press the power button once more to start up your iMac.
Let us know if this helps,

Powermac G5 Squeals, from power supply?

About for the last month I have been hearing squealing from my G5 2.7 Dual in the morning and over my lunch break. The odd thing is it never does it in the evening when I get home from work. This leads me to believe its temperature related because my heat is around 67 until I get home from work which is then 72. Another thing I have noticed is it will squeal whether the computer is on or off. I have put my ear beside the G5 and sounds like it is emitting from the bottom where the power supply is. I am a consumer electronics technician and have the same symptoms on TV's with noisy coils in the power supply, that is helping my theory on the power supply. Has anyone else had this problem or am I one of the few instances, also any help would be appreciated?

Try running SystemLoad once.
http://www.bresink.com/osx/SystemLoad.html
You might try turning off NAP to get rid of the noise.
http://www.macosg.com/group/viewtopic.php?t=2946
-Bmer
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