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?