After searching in many different directions without really finding the beginning of a solution for all problems affecting the iMac 27", Apple seems to have identified the key factor. While everybody was initially thinking that the problem was linked to ATI/AMD GPU, leading to the first firmware update in December, this was not really fixing flickering issues as we reported it couple of weeks ago. It now seems that the firmware of the LCD panel found on some iMac 27" models is the root of almost all problems. The recent firmware update released beginning of this week has solved almost all display problems. This is confirmed by a new after sale procedure sent by Apple to all its certified repair centers with a dedicated application entitled: Apple Service Display Utility or ASDU. It will specifically analyze the display of iMac 27" still affected by some issues despite applying the last firmware update. The procedure is rather long, as the software needs a