Guys, there is a weird noise coming out of my iMac when it gets hot. It sounds like the fan hits something on its rotation, so it goes (teeketeeketeeketee...). When I look at the screen, the noise is coming from the top left corner. It is very annoying. When I bring it back to the store, they don't hear nothing cause the computer doesn't have time to get hot. What could I do ? Is there any way I could look at the fan and see what's wrong with it ? I have never opened my iMac but this is very frustrating. It's not under Apple Care anymore. Thanks for your help.