Despite what my sig says, I have an early 2008 3ghz 8core (I don't know why it says that and I can't figure out how to change it). It simply stays in 32bit mode if I hold down the 6 and 4 keys on startup, but no matter. I've done more research and I believe what Linc Davis says so succinctly is true. Thanks for responding!
2008 Mac Pro can, it is supported on server OS.
Method 1: Startup key combination (for current startup only)
- If your Mac uses the 32-bit kernel by default, but supports the 64-bit kernel, you can start up using the 64-bit kernel by holding the 6 and 4 keys during startup.
- If your Mac uses the 64-bit kernel by default, you can start up with the 32-bit kernel by holding the 3 and 2 keys during startup.
Your Mac will revert to the default kernel the next time you reboot it.
Method 2: On-disk setting (persistent)
To select the 64-bit kernel for the current startup disk, use the following command in Terminal:
sudo systemsetup -setkernelbootarchitecture x86_64
Early 2008 implemented Unified EFI which is 64-bit but you need to run 10.6.x and even then... so much for "64-bit" hardware and OS talk we heard for years.
Even if you cannot or do not boot the Mac OS X Snow Leopard kernel into 64-bit mode, you can run your 64-bit apps as 64-bit, and they can take advantage of all the memory in the machine. This was/is possible even with Mac OS X 10.5 Leopard. The main problem being that there are only a handful of 64-bit applications available as of September 2009.
Somewhere in your "default product" in your profile is where I think the forum pulls that sig