iMac graphics screwing up

Discussion in 'iMac' started by A Macbook Pro, Aug 6, 2011.

  1. A Macbook Pro macrumors 6502

    Aug 22, 2009
    This seems to happen when I watch a HD YouTube video on my 27'' 2011 iMac. What happens is the bottom half of the video gets yellow lines and flickers a bit. A refresh fixes it but once it happens my whole OS X graphics get screwed up. Here is a picture to show what I mean.


    As far as I know only a restart fixes it. Doesn't seem to be occurring in Windows, only OS X Lion.

    Any tips?
  2. s.horsfield macrumors regular

    Apr 3, 2011
    New Zealand
    Wirelessly posted (Mozilla/5.0 (iPod; U; CPU iPhone OS 4_3_5 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8L1 Safari/6533.18.5)

    It's a Lion issue. No fixes as far as I know. Wait for apple to release a update (should be a few weeks time).

    Sorry I couldn't be of more help
  3. A Macbook Pro thread starter macrumors 6502

    Aug 22, 2009
    It's okay, I went on the Apple discussion forums and found another member with exactly the same issue. It's been pinpointed down to the 6970M with 2GB VRAM.
  4. AbeFroman77 macrumors 6502

    May 29, 2010
    No, it's Lion. There's a 40+ page thread so far here:

    There's freezing issues after resuming from sleep and artifacting.
  5. chrono1081 macrumors 604


    Jan 26, 2008
    Isla Nublar
    +1 for Lion issue. My MBA did it last night and a restart fixed it. It never did it in Snow Leopard (well at first until the patch came out).
  6. leeds utd fc macrumors member

    Mar 7, 2009
    Leeds UK
    I'm also having similar problems with my 21.5 entry-level iMac. Stopping it from sleeping seems to have solved the problem - so far.

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