Random pixels on screen, in video and otherwise

Discussion in 'iMac' started by ryanoryan, Jul 27, 2011.

  1. ryanoryan macrumors newbie

    Nov 12, 2009
    My 20" iMac with Snow Leopard has grainy playback, mostly on full-screen video, but also in other video playback, as well as floating pixels around icons in Finder, for example. I have tried changing the resolution but cannot seem to figure out the underlying cause for this problem. See pictures to understand better what I'm referring to, specifically the white speckling on Colbert's jacket and the dots around the Adobe folder.

    Any thoughts?

    Attached Files:

  2. creepy crab macrumors member

    Jun 29, 2011
    How did you capture the images you used in your post?
  3. ryanoryan thread starter macrumors newbie

    Nov 12, 2009
    Standard screen capture (Command + Shift + 4 + Space). They're very representative though. That's what the screen looks like.
  4. creepy crab macrumors member

    Jun 29, 2011
    Well it can't be anything at all to do with your screen, i.e. defective pixels etc, as these would obviously not show up in a screen capture. I wouldn't think it is a resolution problem either, because again surely this would only manifest itself on the image displayed on the monitor, and not on a screen capture... I would think there must be either a problem with the GPU itself, or in the way it is handled by the logicboard before it's translated into the image you see... I'm kinda just thinking outloud here but at the very least it bumped your thread.
  5. cocky jeremy macrumors 68040

    cocky jeremy

    Jul 12, 2008
    Columbus, OH
    I've been getting the same thing since upgrading to Lion. I thought maybe it was my GPU or logic board but i've passed all hardware tests, so i'm pretty sure it's just Lion. For you, i have no idea. I would get your install DVD and run a hardware test first.

    (Restart while holding down D with the disk in)

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