No Buzz, no Dog Whistle, but Humming noise...

It sounds like the hard drive to me. My iMac has a very subtle hum that goes away when the computer goes to sleep. When it's awake the hard drive always spins otherwise it would take too long to read/write if it had to turn up everytime. I noticed on mine if I lift the iMac a little to take pressure of the stand, the humming goes away. This tells me the noise is being transferred through the case, the stand and to my wood desk. Unless my house is absolutely quiet, I don't even notice it anymore.

hummer isn't that bad

My new 27" iMAC is a "hummer" too!

...still, it's pretty darn quiet, and if you buy one for your GF you might be able to multiply the "hummer" factor.

-iamthinking

humming has a electrical or mechanical source , no software will make your iMac hum , apart from bad music recordings , but then the noise comes clearly from the speakers

who got the idea that the iMac have to be total silent , they all make a bit of noise ,if a computer sits direct in front of the ears its normal that everything a normal desktop does is amplified from the aluminium case and thrown at your ears , if you had a MacPro sitting under the desk you would likely hear less noise
so you can either live with it or return it and hope to get one that makes less noise ..good luck


i had been saturday in the apple store and have heard one of the iMac 27" roaring around and it was just idling and did make more noise then my eMac's , so noise is there even on new iMac's

Odds are that it's the hard drive. A 7200 RPM drive can produce a hum at 120Hz. I have a Thermaltake BlacX HD dock, so I put a 1GB WD Black in it and powered it up. The drive produced a 120Hz hum that could actually be felt through the desk when I put my hand on the mouse, or heard with my ear close to the drive. When a computer enters sleep state the HD is usually powered down, but may start later for system purposes.

The physical design of the iMac makes it a perfect sounding board for any mechanical vibrations. In tower designs, the HDs are either mounted on vibration isolation mounts, or tightly clamped down, so the vibrations are highly attenuated.

If the hum is at a lower 50Hz, (60Hz in N America and Japan), it's something resonating in the AC input circuit in the iMac's power supply.

drambuie said:

Odds are that it's the hard drive. A 7200 RPM drive can produce a hum at 120Hz. I have a Thermaltake BlacX HD dock, so I put a 1GB WD Black in it and powered it up. The drive produced a 120Hz hum that could actually be felt through the desk when I put my hand on the mouse, or heard with my ear close to the drive. When a computer enters sleep state the HD is usually powered down, but may start later for system purposes.

The physical design of the iMac makes it a perfect sounding board for any mechanical vibrations. In tower designs, the HDs are either mounted on vibration isolation mounts, or tightly clamped down, so the vibrations are highly attenuated.

If the hum is at a lower 50Hz, (60Hz in N America and Japan), it's something resonating in the AC input circuit in the iMac's power supply.

Click to expand...

the big problem is just a iMac sits direct at same high as your ears are with nothing but the display in between you and all the internals , so in a quiet environment you will hear the slightest hum or click , no matter how hard apple tries to make it quiet
on a MacPro its easier they usually sit under the desk or even inside the
desk so there is less noise finding its way to the ears

when i was picking up my iMac from a apple technician , he had inside his desk a MacPro running around, the door of the desk only slightly open , but we had been chatting around Mac's for a hour or longer and
the Macpro was working all the time and i did not notice a hum or click or even fans from the MacPro, but i could hear the fan of the iMac i was buying from him sitting on the same desk and the iMac was only idling really
but i could hear the fans cpu 1000rpm and hdd 1200rpm and optical 1000rpm , its not loud and not annoying but if you have relative good ears there is evidence of fans inside

Mine has a slight hum, but I have to put my ear up to the screen to hear it. It sounds as if it is directly behind the centre of the screen which would indicate the PSU to be the culprit.

No iMac is going to be 100% silent. If the hum is really bugging you then maybe the iMac is not for you.