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iMac 20" A1224 (EMC 2133) At start up my monitor has vertical lines in red, yellow & gray. When it gets to the point where the sign in screen should show, the screen turns gray. I had to force it to shut down with the power button. Any idea what it is? How do I repair the problem?
Hook it up to an external monitor and tell us your results. UPDATE 8/7/17 Your problem is most likely the GPU (video card) It can be replaced. 70% of the time a reflow of the video card has fixed it in my experience. We have to be careful with costs on a 10 year old machine, but with some effort this can still be a very serviceable machine. Let’s get that external monitor result and we can then look at our options.
