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1.83 GHz Core Duo or 1.83, 2, or 2.16 GHz Core 2 Duo A1208 (EMC 2104/2110/2114/2124)

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Power supply makes a high pitched whine noise

I have a 17" Intel iMac (EMC 2124) that's producing a high pitched whine from the power supply (upper left corner).

It's evident but not very loud when plugged in but turned off. Slightly louder when running, when when shutting down it briefly gets stronger then goes quieter.

I took the computer apart and looked at the PSU, but didn't see any bulging/leaking capacitors or obvious damage.

Is this something I should be concerned about? Should I look for a replacement?

Answered! View the answer I have this problem too

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It's coming from the windings of the power supply's torroidal transformers. High frequencies abound in there. If your computer's not misbehaving, there's usually nothing to worry about. If the noise bugs you, quiet them down by applying some thermally stable nonconducting glue on the windings of the bigger transformers.

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+ very good. The one to put the goop on is the one with copper wire wound around it, but don't cover it due to heat issues.

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Oh wow, never thought of that. I'll try it when I get a chance.

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If this answer solves you problem, please come back and accept it so that others may gain from it. Thanks

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Well, I just tried applying some heat sink compound to the coils (I could try glue later), but as soon as I plugged the unit in the whine was back. Interestingly, I'm only noticing the whine when the unit is plugged in but turned OFF. When it's on, I don't hear it.

When it shuts off, the pitch/loudness of the whine change for a second or so then go back to "normal".

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Nope, heatsink compound won't work. It has to be something that becomes hard.

You still hear the sound even with the power off because the power supply is still energized and draws current (only 4 watts or so) from the mains socket. Pull the plug off the AC mains and the sound should go away.

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I have the some problem Justin was facing. iMac 24 Intel, white. Noise from upper left (looking from front) while computer is plugged it but not powered on. Noise is there when it's sleep too. annoying when I am trying to sleep at night...(I don't want to unplug every night...) Did you find a solution? Change cap? change PSU? or just gave up?

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No, never solved. I ended up giving away the iMac to my mother and stepfather. It's an upgrade for them and they don't notice the whine.

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Umm...not ready to upgrade yet. I wonder if changing the PSU will help. I don't want to unplug my computer every night...

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Good for them! They don't hear the whine because older folks usually suffer from decreased hearing in the high frequency region.

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