No 64-bit stamp

January 11, 2012 7:51 PM

For a fairly new iMac, how do you determine whether the Intel processor is 64-bit or 32-bit?
posted by yclipse to computers & internet (11 answers total)

You can go under the apple menu to About This Mac and then click the "more info" button. Then check this page and match the name of the processor to its speed.
posted by jessamyn at 7:56 PM on January 11, 2012

Go to the EveryMac iMac page, click on your model and look for the 'Architecture'.

I believe it was the move from Core Duo to Core 2 Duo that marked the switch from 32- to 64-bit - which happened around Sept 2006.
posted by nightwood at 7:58 PM on January 11, 2012

Open Terminal.app, and type

uname -p

That should let you know what the processor architecture is: x86 indicates 32-bit and x86_64 indicates 64-bit.
posted by zer0render at 7:58 PM on January 11, 2012

That should let you know what the processor architecture is: x86 indicates 32-bit and x86_64 indicates 64-bit.

I think you mean uname -m there.
posted by Tomorrowful at 8:03 PM on January 11, 2012 [1 favorite]

Is the front plastic? It has a PPC or 32-bit Intel CPU. Is it aluminum and glass? It has a 64-bit CPU.
posted by zsazsa at 8:10 PM on January 11, 2012

nightwood (and the specs he references) are correct. White iMacs from late 2006 and on using a Core 2 Duo processor are 64 bit.

There are some other ways to tell. If you're running Lion, it's on a 64 bit compatible machine.

You don't even need to click the more info button in About This Mac. It will (in Lion at least), tell you the processor and speed. If it doesn't say "Core 2 Duo", it's either newer than that (Core i7) or older (Core Duo). Core 2 Duo is the minimum processor for the 64 bit architecture.
posted by Mad_Carew at 8:58 PM on January 11, 2012

Not true. Even some Pentium 4 processors supported the 64-bit instruction set.
posted by flabdablet at 10:52 AM on January 12, 2012

And uname -m should indeed tell you whether yours does.
posted by flabdablet at 10:55 AM on January 12, 2012

Fabdablet, you are undoubtedly correct, but given the specification of the OP that the subject is iMacs, the switch from PPC to intel was specific to Core processors. I (and possibly others) ignored 64-bit CPUs that were never installed in iMacs.

I am running a 64 bit capable Core 2 Duo, but I'm running 32 bit Snow Leopard.

uname -p and uname -m are showing me i386. I think the uname solution only works if you are currently running a 64-bit OS, not if you're capable of running a 64-bit OS
posted by Mad_Carew at 11:06 AM on January 12, 2012

The version data from uname includes either i386 or X86_64 indicating a 32 or 64 bit kernel. A 32-bit kernel is the default on most Apple computers, and this will still run 64-bit applications under Snow Leopard. Unless you are doing kernel/system-level development there is no need or benefit to running a 64-bit kernel.
posted by Lanark at 12:01 PM on January 12, 2012

How to tell if you’re running the 32 bit or 64 bit kernel in Mac OS X Snow Leopard (I haven't tested but assume this works under Lion as well:

Open the Terminal and type the following command:

uname -a

If you’re using a 32 bit Kernel in Mac OS X:
iMac:~ user$ uname -a
Darwin iMac.local 10.0.0 Darwin Kernel Version 10.0.0: Fri Jul 31 22:47:34 PDT 2009; root:xnu-1456.1.25~1/RELEASE_I386 i386

see the i386 on the end there? That indicates it’s the 32 bit kernel

If you’re using a 64 bit Kernel in Mac OS X:
iMac:~ user$ uname -a
Darwin iMac.local 10.0.0 Darwin Kernel Version 10.0.0: Fri Jul 31 22:47:34 PDT 2009; root:xnu-1456.1.25~1/RELEASE_X86_64 x86_64

the x86_64 at the end will let you know you are using the 64 bit kernel.

You can alternate between the two by holding down “6″ and “4″ during system boot to load the 64 bit kernel, or holding down ’3′ and ’2′ during boot to use the 32 bit kernel. Your machine should default into the kernel that is best supported.

Original source: OSX Daily Hope that helps ya.
posted by Faintdreams at 3:09 AM on January 13, 2012