screen flashes in my iMac
When working today I noticed that my screen was flashing with some rigs across it, is it AC Power failure, heat?
iMac (27-inch Mid 2011), Mac OS X (10.7.3)
I have a mid 2011 iMac and the screen flashed a few times and there was tearing of the screen. It got worse to the point that the Mac would not function even after turning it on and off which was the only way to get rid of the flashing.
I perused the Web and the Apple forum and came across all sorts of info pointing out to screen and board issues. I took the Mac to the Apple Store and the problems was the AMD video card which they replaced since I have Apple care.
Hope this helps.
Armand