I am having the very same issue on my
27" iMac 3.4 GHZ Intel Core i7,
Graphics AMD Radeon HD 6970M 1024 MB running 10.7.4
I bought the computer about 6 months ago and I started to notice the problem about 2 months ago.I called Apple and followed all what they recommeded to do, including reinstalling OS which was a pain.
i don't seem to find a pattern to the flickering but something new just happened, the screen got darker about 4 notches. I restarted and still was darker although the brightness levels bar remains the same at the brightest point.
I do photo retouching and certainly a screen that is not consistent (colour/brightness) is a problem.
Has anyone hear anything new about this problem? Phone support said they couldn't exchange my machine because it does not 'seem' to be a hardware problem... What to do then if there is no software fix?
Thanks.... Getting progressivly mad here!