# Solved: Are iMacs 32-bit or 64-bit?



## number9 (May 15, 2010)

'Scuse the elementary question, but I'm considering getting an iMac--never had a mac b4 so I know zip about them. I see the iMac is available with either 4GB or 8GB RAM. My understanding is that a 32-bit OS can address only a max of 4GB memory [correct?], so with an 8GB-RAM iMac, it must be a 64-bit OS?


----------



## Headrush (Feb 9, 2005)

Without getting too technical, It's no quite as simple as whether its 32-bit or 64bit.

Any newer iMac (2007+) can use more than 4GB memory even though the kernel may only be 32 bit.

For the most part a large majority of the OS X and apps are 64 bit but parts of the OS and included apps are still 32 bit and can run just fine alone side 64 bit ones.


----------



## namenotfound (Apr 30, 2005)

Headrush said:


> Any newer iMac (2007+) can use more than 4GB memory even though the kernel may only be 32 bit.


I thought the logic board of the iMac didn't support more than 4GB until 2009? I could be mistaken though.

My 2010 iMac is listed as supporting up to 16GB of RAM.



number9 said:


> 'Scuse the elementary question, but I'm considering getting an iMac--never had a mac b4 so I know zip about them. I see the iMac is available with either 4GB or 8GB RAM. My understanding is that a 32-bit OS can address only a max of 4GB memory [correct?], so with an 8GB-RAM iMac, it must be a 64-bit OS?


Snow Leopard (10.6) is a 64-bit OS, and that's the OS that's currently shipped with all Macs. Lion (10.7) will be released this summer, so if you're looking to buy a new Mac, I'd wait until Lion comes out so you can buy a computer with it pre-installed (otherwise, you'd have to buy Lion separately).

Also, although Snow Leopard is a 64-bit OS, it handles 32-bit apps just fine. Any app that's compatible with an Intel Mac, will run on Snow Leopard, whether it's 32 or 64-bit.


----------



## number9 (May 15, 2010)

Great info above, thanks.

namenotfound:
"Snow Leopard (10.6) is a 64-bit OS, and that's the OS that's currently shipped with all Macs. Lion (10.7) will be released this summer, so if you're looking to buy a new Mac, I'd wait until Lion comes out so you can buy a computer with it pre-installed (otherwise, you'd have to buy Lion separately)."

Thx for heads-up. I can wait a few months.


----------



## Headrush (Feb 9, 2005)

namenotfound said:


> I thought the logic board of the iMac didn't support more than 4GB until 2009? I could be mistaken though.


These iMacs will support a 4GB DIMM and a 2GB DIMM for a 6GB total. (official spec lists 4GB but 6GB works)

You'll probably ask why not 2 x 4GB for 8GB, but these early iMacs get unstable with that configuration.

P.S. I thought Apple always offered a free upgrade to next OS if you bought your Mac within a specific timeframe before the new OS was released? Not sure what the time frame is though.



namenotfound said:


> Snow Leopard (10.6) is a 64-bit OS, and that's the OS that's currently shipped with all Macs.


It is a 64/32 bit hybrid. On many machines it still defaults to the 32 bit kernel. (All new machines will be 64 bit though, too bad iTunes is still 32bit  )

number9, you might also might be interested in checking out the refurbished section on Apple's site. 
These machines are often indistinguishable from new and come with the exact same full warranty from Apple. (and you can get extended warranty same as new models)

I've bought several iMacs from there and saved several hundreds of dollars one each.


----------



## namenotfound (Apr 30, 2005)

Headrush said:


> On many machines it still defaults to the 32 bit kernel.


True, but if you hold the 4 and 6 keys when booting, it will boot into the 64 bit kernel. Though I've found this causes some problems with 32-bit apps, so I just leave it at the default 32-bit kernel.


----------



## Headrush (Feb 9, 2005)

namenotfound said:


> True, but if you hold the 4 and 6 keys when booting, it will boot into the 64 bit kernel. Though I've found this causes some problems with 32-bit apps, so I just leave it at the default 32-bit kernel.


Doesn't work on my 2007 iMac, though it is suppose to. (Me for the win  )


----------

