i7 with flicker in 64 bit mode?

Discussion in 'iMac' started by 93sr20det, Jan 5, 2010.

  1. 93sr20det macrumors newbie

    Dec 8, 2009
    I have a week 50 machine with the firmware update that flickers only when Snow Leopard is in 32 bit mode. If I boot into 64 bit mode (holding 6 & 4 as the machine boots) it does not flicker. Can anyone else confirm this?
  2. tomacintosh macrumors regular

    Aug 25, 2005
    Interesting point, although shouldn't it be booting in 64-bit anyway?
  3. RealEvil macrumors 6502

    Aug 5, 2007
    Mine does not flicker either way - 32 bit or 64 bit. i dont know if thats useful to, but I suppose somehow the driver may act differently depending on the Kernel mode?

    And, no - iMacs all boot into 32bit Kernel mode. Only certain Mac Pros boot into 64bit kernel by default.
  4. Henryz macrumors newbie

    Dec 10, 2009
    Any advantages to using 64bit as standard?

    (mine doesn't flicker in 32bit)
  5. Yakuza macrumors 6502a


    Jul 24, 2007
    Lisbon, Portugal
    what the hell?

    never heard that one before! And thinking that i already ran in 64bit mode in my MBP with the snow leopard.

    always learning.

    So, being this true, what are the benefits of booting de SL in 64bit mode

    my MBP specs are below it's a late 2006.
  6. RealEvil macrumors 6502

    Aug 5, 2007
    For certain types of applications and actions, 64Bit Kernel will be faster:


    However, some drivers may stop working. I have no issues with anything but I happen to know that certain 3G USB modems do NOT work well with a 64 bit Kernel...

    Mind you, try it out - see if it works for you.

    Note that not many macs actually can run SL in 64Bit Kernel mode... try the following Terminal command:

    ioreg -l -p IODeviceTree | grep firmware-abi

    if it returns '"firmware-abi" = <"EFI64">' you are good to go. If not I believe there is a hack but I am not totally sure how.
  7. 93sr20det thread starter macrumors newbie

    Dec 8, 2009
    After booting my i7 into 64 bit mode for a week I had no flickers. Last night the power went off for about an hour and when the machine restarted it was in 32 bit mode and I had flickers the rest of the night. Can someone else who is having the flicker problems please confirm this for me??????????
  8. tigereat macrumors regular

    Dec 23, 2009

    Call Apple would be better. if they think there is something wrong with your iMac, they might provide a replacement or repair

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