Model A1200 with 2.16 or 2.33 GHz Core 2 Duo processor

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Are Green pixelated lines signs of bad video card?

I just started having this problem today and have done some reading and think it might be my video card.

Problem: I started getting green pixelated lines across the video game I was playing (in Bootcamp). I booted into mac and found the problem was less severe but noticeable in the opening grey screen (faint reddish line shadows), Cover Flow (same green lines but less and fainter) and small areas of web pages. Then I checked watching a movie and it was severe, as in this link:

sample pic

I ran Disk Utilities>Verify Disk. It told me to boot from disk and Repair Disk, which I did and it fixed. I then ran Repair Disk Permissions and Yasu. I also reset PRAM and then did Apple Hardware Test (both short and extended) which came back with no issues detected.

Reading a few threads on this forum I see it might be a video card or LCD issue.

I will try get another monitor to see what that shows when I connect, but in the meantime am wondering if anyone can confirm this just from the image? If it is a video card issue might it be fixable (as in running the fans to cool it more - another issue I've come across in the threads). Or is it time to upgrade my video card?

any help is appreciated! Thanks in advance


EDIT: I connected to external HDTV and the problem was not apparent. Still on the iMac, but not on external display

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2 Answers

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Seems like it is only the blacks that have green lines, the external monitor should give you and idea of whats going on. If the screen looks good on the external monitor then its probably the screen otherwise it might be a faulty GPU. With iMacs unfortunately you can't just upgrade the video card, as far as i know they are welded to the board. I would try that external and let us know what happens. If its still under applecare then you can probably get this problem covered under warranty.

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Thanks for the reply! I just updated above to show that I connected to an external display and it was fine. No occurrence of any of the issues.

And yes, the green lines are only really apparent on darker areas come to think about it.

Is there a way to figure out if it's the monitor or GPU? No applecare any more unfortunately. Also I'm in the Bahamas so no just popping down to the local genius bar! If it's something replaceable I have tech-friends that will help do it. I had to replace the power supply last year (and then get a new hard drive). Maybe should have mentioned that above.

If it is the monitor is it possibly a fixable issue? Or should I just move my HDTV and use that as a monitor? (Also, this might be a great fix seeing as it will mean I can watch movies better in bed!)


I believe it could be an issue with the monitor then you can try this its an apple hardware test. it seems that if the external is working fine then the GPU is most likely ok. I would also think maybe just to connection from the GPU to the internal monitor is bad and the external link is good its just odd that just the darker areas are bad and GPU seems fine(computers can be wierd). The genius bar could probably tell you whats wrong but there are replacement screens sold that you may be able to find(I would give you a link but i don't know ur exact model#). I would just use the computer as a tower and use the HDTV as a monitor(free fix), probably a better picture and bigger than the built in screen depending on what your tv looks like.


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Thanks. I did already run the Apple Hardware Test and both the short and extended tests came back with no issues.

My TV is a 32" 720p JVC, so definitely an upgrade in screen real estate. I only use it to watch movies so at least now it will be put to some use. Will have to move my chair back a bit though using it as a desk

I will look into it more to see if I can fix it, but certainly in the meantime looks like I have a solution.

Also just to check, if the LCD problem worsens can it affect anything else? Or having the external monitor will mean even if it does I'm covered?

thanks for your help!

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