So i got my 27 inch core i7 imac and constantly heard a whistle kind of noise, i brushed it off and thought i was insane. My friend came over today and sat at my computer and said what the hell is that buzzing? So we turned off my imac and it stopped. I turned it back on and it didn't do it, then when i put my brightness upp the way up i heard the whistle!. i looked it up online and it seems like a pretty common issue... i have a 2.8 i7 model from last year. For paying 2400 for a computer this doesn't seem okay to me. What should i do?