Apparently an Intel Mac will only boot into true 64-bit mode in Snow Leopard if it has the appropriate EFI. ----------------- According to a post on Gizmodo: Any Mac with 64-bit EFI will be able to boot with a 64-bit kernel. To check if your Mac has 64-bit EFI, open up Terminal and enter: ioreg -l -p IODeviceTree | grep firmware-abi It will say either EFI32 or EFI64. EFI64 means you can use the 64-bit SL kernel. --------------------- I have a 2006 Mac Pro bought the day they were released in August 2006. The response I got was that it is 32-bit, which I knew from issues regarding video card upgrades over the past few years. I did not know that means Snow Leopard is a bust for me. Can anyone confirm that my very expensive Intel Mac Pro is now officially outdated? Just upgraded to 12 GB ram in preparation for 10.6. 64-bit was a major selling point!!