24" iMac screen hum: serious issue?

[bumzo1]

I bought a 24" iMac back in march and immediately installed an app to boost my fan speed so that it doesn't run so hot. I recently turned it down and now I'm noticing a very annoying hum that can only be heard when the brightness is turned down. I've tried keeping the brightness up but it hurts my eyes, especially when reading forums and such. I've searched MROOGLE and some other people have the same problem. Is this something I should be worried about? I have AppleCare through 2012.

Thanks

 

[flopticalcube]

Its a bad inverter board. Its an easy fix for Apple. Call them.

 

[bumzo1]

I'll make sure to do that. How long will it take to fix it? I practically live in front of my computer.