iMac making constant buzzing/humming noise

Mitch2742 wrote:

My iMac 27" started buzzing a few weeks ago. After perusing the internet for a solution, I found a post someone made suggesting that it could something plugged in--anywhere in your home--that may be interfering with the power that reaches the computer. In his case, it was a lamp. I tried unplugging various appliances to try and stop the buzzing, to no avail. Then, one Thursday night, the buzzing stopped. I was excited, but still skeptical. The only thing that had changed was that my roommate had left for a weekend trip.

My iMac remained silent for the rest of the weekend. When my roommate got back, it started up again. It continued to buzz constantly throughout the week, and I was tempted to take it into the Apple Store, but then my roommate--who I've yet to share any of this with--told me he was going on another weekend trip. I figured I'd wait to see if the buzzing once again stopped when he left, which was tonight. Sure enough, it's been silent all evening and night, leading me to believe that something he's been plugging in in his room has been the cause of the buzzing. I'm pretty relieved, to be honest, because it's less than six months old and I really didn't feel like making the long drive to the closest Apple Store.

So yeah--go around your house and unplug random things, no matter what room they're in.

Better yet get yourself a high quality UPS with some line conditioning built in. I suspect you have it plugged into a plug strip, inexpensive surge protector or directly into the wall. Dirty power is the cause of many computer failures, in your case protect your investment buy giving it clean power.

Thanks Mitch - this helped. I found the culprit for me was the 6-way extension socket the iMac was plugged into. Although only two other slots were being used (for external hard drives) when i plugged the iMac directly into the wall socket the noise went instantly.

It's covered by a 1 year warranty, take it into your local Apple Store or AASP to be looked at.

Hi, what all do you have connected?

It may be a ground loop problem.

Look up ground loop in a dictionary. In short it means you may have a grounding problem with the power getting to the computer.

It could be the harddrive. Make sure you backup anything you care about.

Hi, My iMac has this problem too. I called apple, apple advisor asked me to send my iMac to apple store to check it up.

What's your solution?

My iMac 27" started buzzing a few weeks ago. After perusing the internet for a solution, I found a post someone made suggesting that it could something plugged in--anywhere in your home--that may be interfering with the power that reaches the computer. In his case, it was a lamp. I tried unplugging various appliances to try and stop the buzzing, to no avail. Then, one Thursday night, the buzzing stopped. I was excited, but still skeptical. The only thing that had changed was that my roommate had left for a weekend trip.

My iMac remained silent for the rest of the weekend. When my roommate got back, it started up again. It continued to buzz constantly throughout the week, and I was tempted to take it into the Apple Store, but then my roommate--who I've yet to share any of this with--told me he was going on another weekend trip. I figured I'd wait to see if the buzzing once again stopped when he left, which was tonight. Sure enough, it's been silent all evening and night, leading me to believe that something he's been plugging in in his room has been the cause of the buzzing. I'm pretty relieved, to be honest, because it's less than six months old and I really didn't feel like making the long drive to the closest Apple Store.

So yeah--go around your house and unplug random things, no matter what room they're in.

I've just got my iMac 27" (bought October 2011) back from the Apple technical department where they explained the buzzing/ fluttering noise was a result of a poor power supply. They fixed it the same day.

I'm not an expert, but the explanation was that it was the area of the iMac that converts the power supply to the usable form that the computer needs. This wasn't working properly. I was in warranty, so I can't comment on costs to fix it normally.

I asked whether I was doing anything wrong (such as leaving the iMac on all the time) and he didn't think so (their iMac's in the department are on 24 hours a day and they haven't come across this themselves).

I've had this same problem for a few months now. My machine is only a year and a half old, but it was silent for the first 15 months. Now it's not.

It sounds like it should be a fan, but it's not affected by any changes in fan speed or temperature. My iStat shows no anomolies, nor has Hardware checker been able to detect anything.

I have in fact had it in (we don't have apple stores in Peoria, IL, so I have to go to an authorized service center) and we still have an open ticket on it. Of course, right before I took it in it got quiet again and stayed that way for the entire three days it was in the repair shop. It stayed that way for another week and a half after I got it back. Then the noise started back up again.

The noise is directly affected by the brightness control (brighter=louder.) Only two other things have been able to stop it, even temporarily. SMC reset (inconsistently) and unplugging it after I shut it down. If I leave it overnight, plug it back in and start it up, it's quite usually until it goes into sleep mode. When I wake it up again the noise returns.

All of the Apple techs I've talked to say they have no idea what it is. Well, it's something and I'm hearing it right now. It's very much like the sound you hear on this video:

http://youtu.be/bgQk6HMAeMc

The poster claims to explain how to fix it, but doesn't really. What it shows is an iMac with the front screen removed and him sticking a pecil tip in one of the vents to stop the noise. The sound in this video appears to be coming from "LCD tape" which appears to be some kind of film coming from the LCD panel. Perhaps someone with apple expertise could explain this a little better.

So, if any of you (including apple techs reading this) have a chance to view this, what would be the best way to describe this? Better yet, how do we fix it or stop it from recurring?

I'm pretty sure the reason few people find a solution is because they assume its a fan making the noise, and the tech natually follows up on that hunch instead of pursuing some other leads. But if it's not a fan, and we don't know what else it's supposed to be, what do we tell tech support so that we can get this fixed. It's annoying, and I didn't have to put up with it earlier? And I certainly never heard this amount of noise coming from a Windows machine...

Thanks in advance to anyone who can bring us closer to solving this once and for all.

I am having the same problem with my 15'' mbp retina display

I have absolutely no idea what is going on with it.

did you ever figure out what it was?

So it's been forever since my above post but I thought I'd drop in an day that it was NOT interference - the buzzing started again soon afterward and it ended up being a faulty power supply. Took it into the Apple Store that week and it's been buzz free ever since.

I had exactly the same issue, an annoying low humming noise that I thought was coming from my iMac ?
Took me ages to discover the cause.
I run an external back up hard drive for Time Machine.
Not exactly being the tidiest of workers, my desk is normally very cluttered.
I discovered a pack of post-it-notepads had somehow tucked itself under the corner of my external hard drive so it was no longer sitting flat.
As soon as I rectified this problem solved.
Thank God I never took my iMac to the Apple Store, they would never have found this fault :-)