Can't boot into 64-bit mode

Discussion in 'macOS' started by bailorg, Mar 9, 2011.

  1. bailorg macrumors member


    Dec 16, 2008
    I'm have a 2008 aluminum unibody Macbook with EFI64 (yes, I double-checked)

    I just upgraded to 8gb of RAM and I am trying to run Rember to test the memory.

    However, in 32-bit kernel mode, Rember returns a "memory lock" error because my system has over 4gb of RAM.

    I have tried shutting down and holding 6 and 4 and then pressing the power button, but every time I do this, the system still boots into 32-bit mode.

    Is there a proper time to hold down 6 and 4?

    Do I press them before or immediately after pressing the power button?

    When can I let them go?

    Are there drivers or programs starting on login that prevent the system from booting into 64-bit mode?
  2. MarkMS macrumors 6502a

    Aug 30, 2006
  3. Ramasjang macrumors member

    Feb 22, 2009

    I have a late 2008 2GHz macbook also with 8GB ram...

    I can't boot into 64bit neither.

    Any help out there?
  4. atlanticza macrumors 6502a


    Jul 18, 2008
    Cape Town
    Hold down the '6' and '4' keys when the Mac starts up (until the Apple log). After starting up in 64-bit mode, check About This Mac…, click More Info, then click on Software. In 64-bit mode there will be a yes next to 64-bit Kernel and Extensions.

    If not, see if this helps
  5. alust2013 macrumors 601


    Feb 6, 2010
    On the fence
    The aluminum MB needs some sort of hack to use 64-bit kernel, and will not work with the default 6 and 4 key startup
  6. bailorg thread starter macrumors member


    Dec 16, 2008
    Is there some reason for this beyond "Apple said so"?

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