Screen flickering: Intel-based iMacs also affected

Yesterday, we reported on an issue where some MacBook Pro Core 2 Duo (Late-2006) units exhibit screen flickering or suffer from appearance of horizontal distortion lines in an issue is reminiscent of a problem that plagued some iBook G4s, generally resolved by logic board replacement.

It now appears that this problem also affects some Intel-based iMacs -- both the early-2006 (Core Duo) and late-2006 (Core 2 Duo) models. Unfortunately, there does not appear to be a solid hardware-based fix for this problem yet, as some users having parts replaced under warranty report that their purportedly repaired machines still exhibit the issue.

Potential software-based fixes include disabling screen dimming in the Displays pane of System Preferences and setting the display to never sleep in the Energy Saver pane of System preferences.

If either of these suggestions works for you, please let us know.

MacFixIt reader Olivier Martin writes:

"I've been experiencing this issue for several months now, simple to reproduce : set the display to suspend after 1 minute, let it go dark, move your mouse and voila, the display is completely distorted. I've checked the forums and lots of people have it too. I hoped that the latest EFI 1.1 update I did 10 minutes ago would fix it but it did not."

"When it happens I have to shut it off for several hours for the display to become normal again."

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