Hello everyone, Been using my 27" Imac for slightly over a week now and have noticed some issues. There is an audible buzz/scratching sound every time machine goes into power saving mode or when screen is dimmed, it sounds exactly the same as http://www.youtube.com/watch?v=jXyH1XGFFck The machine is dead silent when screen is at full brightness though. The buzz/scratching sound only happens in dim and power saving mode when machine is warm; its extremely annoying. Does anyone else have this problem too? Mine's a W8006 and the lower portion in the middle of the screen is yellowish as well.