Model A1312 / Mid 2010 / 3.2 GHz Core i3 or 2.8 & 3.6 GHz Core i5 or 2.93 GHz Core i7, ID iMac11,3

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iMac 27 2010 low brightness buzzing noise

Hello community,

I have recently bought an iMac 2010 27 inch. Everything is okay with the machine but it makes a strange buzzing noise while the brightness is turned down. Even below 90% I can notice a quiet buzz.

Browsing through the Internet, I found out that the problem might be related to the PSU or the display inverter. Latter makes more sense because lower brightness means lower power consumption for the PSU, doesn’t it?

Should I open the iMac to examine where the noise comes from exactly? Where would I be able to buy spare parts?

Hoping for a reply,


Answer this question I have this problem too

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There are two parts which control your backlight The driver board which supplies the power and the controller which is on the back of the LDC panel.

Here is the IFIXIT guide to replace the driver board: iMac Intel 27" EMC 2390 LED Driver Board Replacement and heres the needed part: Backlight Board - Apple P/N 661-5576 I would start there.

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Hey, thanks for the quick answer. Yesterday I disassembled my iMac to make sure it is the LED driver board making the buzzing sound. But instead, I was sure it is the power supply, I even unscrewed the LED Driver board from the case and separated it to be sure it is the power supply.

After putting all back together the noise was gone. I also noticed the iMac being much cooler than before where it was running hot even from listening to music. Sadly, the buzz returned today after a few hours of usage.

What should I do now? Buy a new power supply?

Thanks for answering,



If you think the power supply is the source of the buzzing then I guess you'll need to replace it.


Thanks for your answer, then I'm going to buy one and tell how it's going to turn out. Power supplies for the 2011 27inch iMac do also fit, don't they? And it doesn't matter which manufacturer it's coming from, does it?

Thanks for your help


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Leon will be eternally grateful.
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