Chosen Solution
I have a iMac 17" 1.83 Core Duo with the well known vertical line problem. From what I understand they are caused by defective multiplexers in the screen itself. Now I have a second iMac of the same series with a defective mainboard but good screen! I could swap-out the screen from the other iMac with the vertical lines. But! I heard that the vertical lines where caused by a defect in the mainboard, so that they will come back very quickly. Is this true? Or can I save the system by replacing the screen?
Hook it up to an external monitor to isolate the issue. If you have a bad GPU the lines will be on the external. Let us know your results.
