How to Enable 64 bit in Snow Leopard & Leopard
Here’s how to tell if you’ve successfully loaded the 64-bit kernel in Snow Leopard: This will work on Macbook Pro’s, Mac Mini, Imac’s and Mac Pro Desktops
Does running a 64-bit kernel have an impact on applications I usually run?
No, but it can have a significant impact on kernel extensions, usually used to enable third-party product hardware and special features. 32-bit kernel extensions will not work when your computer is running a 64-bit kernel. Products that use 32-bit kernel extensions may not work or may not recognize their associated hardware. Learn more about compatibility with the 64-bit kernel.
The entire computing industry is moving from 32-bit to 64-bit technology, and it’s easy to see why. Today’s Mac computers can hold up to 32GB of physical memory, but the 32-bit applications that run on them can address only 4GB of RAM at a time. 64-bit computing shatters that barrier by enabling applications to address a theoretical 16 billion gigabytes of memory, or 16 exabytes. It can also enable computers to crunch twice the data per clock cycle, which can dramatically speed up numeric calculations and other tasks. Earlier versions of Mac OS X have offered a range of 64-bit capabilities. Now Snow Leopard takes the next step in the transition from 32-bit to 64-bit.
Can I switch between the 64-bit kernel and 32-bit kernel?
Yes. Switching to the 32-bit kernel will let you use products that use 32-bit kernel extensions.
- Launch System Profiler (Applications > Utilities > System Profiler or About This Mac > More Info…)
- Click on the “Software” heading in the left pane
- Check the “64-bit Kernel and Extensions” line for a Yes or a No.
This is what it looks like in 32-bit:
This is what it looks like when the 64-bit kernel and extensions are loaded:
How to enable 64bit mode if you are running 32bit.
Open the program Terminal – Applications -> Terminal
Type:
sudo pico /Library/Preferences/SystemConfiguration/com.apple.Boot.plist
You will be prompted next to enter your password.
Add the string “arch=x86_64”
Ex:
<key>Kernel Flags</key>
<string>arch=x86_64</string>
Control-X to exit with prompting to save.
Reboot your computer and you’re done.
