Answer to: Backlight make buzzing soundI know this is an old thread, but this just happened to me and I found this first on google. If you find the noise is coming from your transformer and you don't want to find a new transformer and take apart your monitor to fix it, then you may be able to use this easy workaround to get rid of the noise. (Worked for me.) I was powering my MacBook Pro with the MagSafe cable attached to my Cinema Display. I disconnected the Apple Cinema display's MagSafe cable from my MacBook Pro. I used the separate power adapter that came with my MacBook Pro to power my MacBook Pro. I left the MagSafe cable connected to the Cinema Display disconnected. The noise is gone and everything is working fine.