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On startup, I see a corrupted video stream as above. Recently replaced stock video board because I wasn't getting any video output. Any ideas on what might be wrong and how I can fix it?

  • Does it do that if you start up in Safe mode (press shift)
    – Ruskes
    Oct 3, 2014 at 2:47
  • Yes - the squiggly lines are still there.
    – mxbag
    Oct 3, 2014 at 4:07
  • Did the replacement video board ever work ? It looks like loose cable contact to me.
    – Ruskes
    Oct 3, 2014 at 4:49

1 Answer 1


It seems that you're seeing two problems simultaneously: video corruption and a software error returned by your antivirus application. This suggests that the system has possible hardware issues. I would boot the system to the Apple Hardware Test and run diagnostics to see whether there is a hardware failure. Video corruption is often traceable to a bad GPU and/or bad RAM. Since you replaced the video card, the bad GPU is unlikely.

If AHT returns errors, you may wish to take the system into a Genius Bar or authorized Apple repair centre for further evaluation. If not, you may have a transient issue. You can try swapping around/removing RAM to determine if one or more of your SO-DIMMs have gone bad.

  • Thanks for your suggestion. The antivirus application was deleted a long time ago, however, the pop-up at start-up remains. I can try the DIMM swap. I hear Apple often replaces the logic board as a matter of course and I wanted to isolate the cause as much as possible before taking the unit to Apple.
    – mxbag
    Oct 3, 2014 at 4:14
  • If you're seeing startup messages, you still have remnants of the AV software in your system launch daemons. AV software generally cannot be deleted merely by dragging the app to the Trash and emptying because they splatter stuff deep inside the System folders. Oct 3, 2014 at 7:49
  • Well the screen has cleared up a bit on its own (still has squiggly lines). New symptom: When trying to open ANY jpeg in preview, the content screen is blank white. I have not done anything to the unit yet. What think you?
    – mxbag
    Oct 3, 2014 at 17:16
  • You can try reinstalling OS X and then apply all updates to see whether that fixes it, but I still think you have hardware problems. Oct 4, 2014 at 5:00

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