These Macs use the 64-bit kernel by default in Mac OS X v10.6.
- Mac Pro (Mid 2010)
- MacBook Pro (Early 2011)
- iMac (21.5-inch and 27-inch, Mid 2011)
These Macs use the 64-bit kernel by default in Mac OS X Server v10.6 (they can also use the 64-bit kernel in Mac OS X v10.6, but do not use it by default).
- Xserve (Early 2008) and later
- Mac Pro (Early 2008) and later
- Mac mini (Mid 2010)
These Macs support the 64-bit kernel, but do not use it by default.
- iMac (Early 2008) and later
- MacBook Pro (Early 2008 through Mid 2010)
You can see which kernel you are using in System Profiler:
- Choose About This Mac from the Apple () menu.
- Click More Info.
- Select Software in the Contents pane.
- Look for "64-bit Kernel and Extensions: Yes (or No)" under the System Software Overview heading.
Some third-party software may need to be updated for compatibility with the 64-bit kernel. Learn how to switch between using the 64-bit and 32-bit kernels. Note: A 64-bit kernel is not the same thing as a 64-bit processor.