I’m running Mac OS 10.6.4 on my Mac Pro, and I’m confused about 32-bit and 64-bit. What will happen if I restart my Mac holding the 6 and the 4 keys down to boot up into 64-bit? Nobody seems to know at my Mac User Group, so I’d love to share your answer with them.
When you hold down the 6 and 4 keys on the keyboard during a bootup cycle, you are manually forcing your Intel Mac to search for a 64-bit version of the EFI firmware and subsequently boot into 64-bit Mac OS X, if your computer supports 64-bit.
With a 64-bit system, information can be processed much faster because the processor can handle 64-bit chunks of data, instead of 32-bit chunks. In 32-bit mode, an application can only address up to 4GB of memory, while the 64-bit mode allows for memory addressing of up to a theoretical 16EB (each exabyte is 1 billion gigabytes).
My Mac's firmware is 64-bit...