Check your backlight
I am on my 3rd 27" iMac i7. All of them have had annoying backlight issues. The first two made an electrical buzz when dimmed. The one I'm using now is silent when dimmed, but creates a dog whistle noise when increasing the brightness level...this high pitched frequency is sustained when brightness reaches a certain level. In all cases, the noisy backlight could only be heard when the iMac had been on for more than a couple of minutes, or reached a certain temperature.
I got all of these machines from a nearby Apple retail store. At this particular store, I dealt with two different geniuses that were very helpful, and--though the sound could not be heard in the store--they gladly switched out the computer...twice. Assuming they had been sent a bad batch after discovering a 3rd noisy backlight, I packed up the machine for what I hoped would be the last time and drove it to a retail store location further from my house. Seemed like a good idea at the time.
The genius I spoke with there was not particularly helpful, in fact he sort of made me feel crazy because he couldn't hear the sound seconds after powering up the machine in that noisy store. He ran some pointless diagnostics test and basically said that he couldn't help me and that "he wouldn't worry about it," and that "it's probably normal." (I am not convinced this is normal...especially because I don't hear the whistle until the machine gets warm...not to mention that I just went through two others that did not whistle.) I was tempted to ask for a full refund, but I really can't be without this machine, and I didn't want to be hit with a restocking fee since the "genius" didn't consider the computer defective. I decided to take it home and try to live with it.
It's worth noting that none of the 27" iMacs I brought home had dead pixels, yellowing, or any other common display problems. All three would have been perfect if not for the backlight issues (display issue? inverter? PSU?). All of this swapping and exchanging has me feeling like a pest, but it is very quiet where I have the computer, and I must manage the sound in this environment the best that I can since I work with a lot of audio. As I type this, I can hear the dog whistle...subjectively getting louder as my ears hone in on it. This may well drive me insane.
I spent a decent amount of money on a machine that is going to essentially be my workstation for the next few years. I see no reason why it should have problems out of the box. Not sure what I'm going to do about it though.
I am on my 3rd 27" iMac i7. All of them have had annoying backlight issues. The first two made an electrical buzz when dimmed. The one I'm using now is silent when dimmed, but creates a dog whistle noise when increasing the brightness level...this high pitched frequency is sustained when brightness reaches a certain level. In all cases, the noisy backlight could only be heard when the iMac had been on for more than a couple of minutes, or reached a certain temperature.
I got all of these machines from a nearby Apple retail store. At this particular store, I dealt with two different geniuses that were very helpful, and--though the sound could not be heard in the store--they gladly switched out the computer...twice. Assuming they had been sent a bad batch after discovering a 3rd noisy backlight, I packed up the machine for what I hoped would be the last time and drove it to a retail store location further from my house. Seemed like a good idea at the time.
The genius I spoke with there was not particularly helpful, in fact he sort of made me feel crazy because he couldn't hear the sound seconds after powering up the machine in that noisy store. He ran some pointless diagnostics test and basically said that he couldn't help me and that "he wouldn't worry about it," and that "it's probably normal." (I am not convinced this is normal...especially because I don't hear the whistle until the machine gets warm...not to mention that I just went through two others that did not whistle.) I was tempted to ask for a full refund, but I really can't be without this machine, and I didn't want to be hit with a restocking fee since the "genius" didn't consider the computer defective. I decided to take it home and try to live with it.
It's worth noting that none of the 27" iMacs I brought home had dead pixels, yellowing, or any other common display problems. All three would have been perfect if not for the backlight issues (display issue? inverter? PSU?). All of this swapping and exchanging has me feeling like a pest, but it is very quiet where I have the computer, and I must manage the sound in this environment the best that I can since I work with a lot of audio. As I type this, I can hear the dog whistle...subjectively getting louder as my ears hone in on it. This may well drive me insane.
I spent a decent amount of money on a machine that is going to essentially be my workstation for the next few years. I see no reason why it should have problems out of the box. Not sure what I'm going to do about it though.
