Is my iMac 64 bit?!

mark66 · 11 Jan 2011 at 23:00

Hi,

I have just upgraded to 10.6 as I want to install Windows 7 using Bootcamp. I had presumed my mid 2008 24" 3ghz iMac was 64 bit and so ordered a Windows 7 Home Premium OEM 64 bit.

However I happened to look through the Bootcamp manual (10.6) and read the following on page 5:

You can use a 64-bit version of Windows Vista or Windows 7 with any of these Mac computers:

A Mac Pro or MacBook Pro introduced in early 2008 or later
An iMac or MacBook introduced in late 2009 or later

This made me question whether mine was 64 bit or not! On checking 'About this Mac' it says I have a 3.06Ghz Intel Core 2 Duo.

On checking Everymac.com it states that my architecture is 64 bit.

Looking at this Mac Rumours forum post, it looks like I am not the only one who is not sure, with some saying yes and others saying no!

All Core 2 Duo processors are 64-bit

The first Core 2 Duo Macs were all 32 bit machines.

Can someone shed any light here? I was just about to send my Windows 7 back to get a 32 bit version.

Seems strange that Apple should state that only late 2009 iMacs are compatible with W7 64bit?

Cheers :confused:

artaxerxes · 12 Jan 2011 at 00:11

Depends on your EFI

http://discussions.apple.com/thread.jspa?messageID=12596731

But there may be a work around in the post above.

mark66 · 12 Jan 2011 at 08:38

Thanks, glad its not me be just being thick!

Ok, I followed the instructions in one of the links and issue the command:

ioreg -l -p IODeviceTree | grep firmware-abi

Which gave me the result "EFI64" so it is 64 bit...

The link states that I can now boot into the 64 bit kernel by holding down the 6 & 4 buttons or edit the boot.plist so that OSX does it automatically.

I haven't done this yet, is there anything I will see differently to show that I am running on the 64 bit kernel or is it all 'behind the scenes' as it were? Should I expect to see a performance gain? Is there an easy way to test this gain if?

And finally, even though Apple states Windows 7 64 bit is for iMacs of late 2009 onwards, should I ignore this and just go with it?

Cheers!

Mark

CrispyXUK · 12 Jan 2011 at 13:07

Barely any gain.