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MacOS X 10.6 "Snow Leopard" Q&A - Updated December 8, 2010

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Which Intel Macs have 64-bit processors? Which have a 64-bit EFI? Which are capable of booting MacOS X 10.6 "Snow Leopard" in 64-bit mode?

With the exception of the "Mid-2010" Mac Pro models, Intel Macs boot Snow Leopard in 32-bit mode by default, and it's a bit complicated to sort out which Macs really are capable of booting MacOS X 10.6 "Snow Leopard" in 64-bit mode.

Intel Core Solo and Core Duo processors are 32-bit and consequently Macs with these processors only are capable of booting in 32-bit mode.

Intel Core 2 Duo and Xeon processors are 64-bit. However, based on reader reports, e-mail and twitter received, as well as hands-on observation, it is believed that all Macs with 64-bit processors released in 2006 only have a 32-bit EFI, and consequently, only are capable of booting in 32-bit mode. This is of particular disappointment to owners of the first Mac Pro, which despite having a powerful 64-bit processor no doubt has had its "working life" cut short by a 32-bit EFI.

Furthermore, it appears that although subsequently released MacBook, MacBook Air, and pre-"Mid-2010" Mac mini models all are equipped with "Core 2 Duo" 64-bit processors and 64-bit EFIs, Apple has blocked these "consumer-targeted" Macs from booting in 64-bit mode. iMac and MacBook Pro models released in 2007 with 64-bit EFIs seem to have been blocked as well.

It isn't yet clear if this block is simply an effort to keep consumers -- who are less likely to need to boot in 64-bit mode for the time-being -- from running into possible kernal extension compatibility issues or rather a "forced" (albeit blurry) product differentiation between "consumer" and "professional" product lines. Previously, Apple has blocked hardware capabilities in software -- external display support on iBook models, for example -- in an effort to protect the profit margins of higher-end systems. Regardless, clever hackers have figured out ways around the EFI block.

The below chart is believed to be accurate. However, it should be considered speculative and subject to possible revision. Should you have additional or contradictory information, please share.

Mac

Processor

EFI

Boot

iMac "Core Duo" 1.83 17-Inch

32

32

32

iMac "Core Duo" 2.0 20-Inch

32

32

32

iMac "Core Duo" 1.83 17-Inch (IG)

32

32

32

iMac "Core 2 Duo" 1.83 17-Inch (IG)

64

32

32

iMac "Core 2 Duo" 2.0 17-Inch

64

32

32

iMac "Core 2 Duo" 2.16 20-Inch

64

32

32

iMac "Core 2 Duo" 2.16 24-Inch

64

32

32

iMac "Core 2 Duo" 2.0 20-Inch (Al)

64

64

32*

iMac "Core 2 Duo" 2.4 20-Inch (Al)

64

64

32*

iMac "Core 2 Duo" 2.4 24-Inch (Al)

64

64

32*

iMac "Core 2 Extreme" 2.8 24-Inch (Al)

64

64

32*

iMac "Core 2 Duo" 2.4 20" (Early 2008)

64

64

32/64

iMac "Core 2 Duo" 2.66 20" (Early 2008)

64

64

32/64

iMac "Core 2 Duo" 2.8 24" (Early 2008)

64

64

32/64

iMac "Core 2 Duo" 3.06 24" (Early 2008)

64

64

32/64

iMac "Core 2 Duo" 2.66 20" (Early 2009)

64

64

32/64

iMac "Core 2 Duo" 2.66 24" (Early 2009)

64

64

32/64

iMac "Core 2 Duo" 2.93 24" (Early 2009)

64

64

32/64

iMac "Core 2 Duo" 3.06 24" (Early 2009)

64

64

32/64

iMac "Core 2 Duo" 2.0 20" (Early 2009)

64

64

32/64

iMac "Core 2 Duo" 3.06 21.5" (Late 2009)

64

64

32/64

iMac "Core 2 Duo" 3.06 27" (Late 2009)

64

64

32/64

iMac "Core i5" 2.66 27" (Late 2009)

64

64

32/64

iMac "Core i3" 3.06 21.5" (Mid-2010)

64

64

32/64

iMac "Core i3" 3.2 21.5" (Mid-2010)

64

64

32/64

iMac "Core i3" 3.2 27" (Mid-2010)

64

64

32/64

iMac "Core i5" 2.8 27" (Mid-2010)

64

64

32/64

MacBook "Core Duo" 1.83 13"

32

32

32

MacBook "Core Duo" 2.0 13" (White)

32

32

32

MacBook "Core Duo" 2.0 13" (Black)

32

32

32

MacBook "Core 2 Duo" 1.83 13"

64

32

32

MacBook "Core 2 Duo" 2.0 13" (White/06)

64

32

32

MacBook "Core 2 Duo" 2.0 13" (Black)

64

32

32

MacBook "Core 2 Duo" 2.0 13" (White/07)

64

64

32*

MacBook "Core 2 Duo" 2.16 13" (White)

64

64

32*

MacBook "Core 2 Duo" 2.16 13" (Black)

64

64

32*

MacBook "Core 2 Duo" 2.0 13" (White-SR)

64

64

32*

MacBook "Core 2 Duo" 2.2 13" (White-SR)

64

64

32*

MacBook "Core 2 Duo" 2.2 13" (Black-SR)

64

64

32*

MacBook "Core 2 Duo" 2.1 13" (White-08)

64

64

32*

MacBook "Core 2 Duo" 2.4 13" (White-08)

64

64

32*

MacBook "Core 2 Duo" 2.4 13" (Black-08)

64

64

32*

MacBook "Core 2 Duo" 2.0 13" (Unibody)

64

64

32*

MacBook "Core 2 Duo" 2.4 13" (Unibody)

64

64

32*

MacBook "Core 2 Duo" 2.0 13" (Wh-09)

64

64

32*

MacBook "Core 2 Duo" 2.13 13" (Wh-09)

64

64

32*

MacBook "Core 2 Duo" 2.26 13" (Uni-09)

64

64

32*

MacBook "Core 2 Duo" 2.4 13" (Mid-2010)

64

64

32*

MacBook Air "Core 2 Duo" 1.6 13" (Orig)

64

32

32

MacBook Air "Core 2 Duo" 1.6 13" (NVI)

64

64

32*

MacBook Air "Core 2 Duo" 1.86 13" (NVI)

64

64

32*

MacBook Air "Core 2 Duo" 1.86 13" (09)

64

64

32*

MacBook Air "Core 2 Duo" 2.13 13" (09)

64

64

32*

MacBook Air "Core 2 Duo" 1.4 11" (10)

64

64

32*

MacBook Air "Core 2 Duo" 1.86 13" (10)

64

64

32*

MacBook Pro "Core Duo" 1.83 15"

32

32

32

MacBook Pro "Core Duo" 2.0 15"

32

32

32

MacBook Pro "Core Duo" 2.16 15"

32

32

32

MacBook Pro "Core Duo" 2.16 17"

32

32

32

MacBook Pro "Core 2 Duo" 2.16 15"

64

32

32

MacBook Pro "Core 2 Duo" 2.33 15"

64

32

32

MacBook Pro "Core 2 Duo" 2.33 17"

64

32

32

MacBook Pro "Core 2 Duo" 2.2 15" (SR)

64

64

32*

MacBook Pro "Core 2 Duo" 2.4 15" (SR)

64

64

32*

MacBook Pro "Core 2 Duo" 2.4 17" (SR)

64

64

32*

MacBook Pro "Core 2 Duo" 2.4 15" (08)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.5 15" (08)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.5 17" (08)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.4 15" (Uni)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.53 15" (Uni)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.66 17" (Uni)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.66 15" (Uni)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.26 13" (SD)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.53 13" (SD)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.53 15" (SD)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.66 15" (SD)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.8 15" (SD)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.8 17" (09)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.4 13" (10)

64

64

32/64

MacBook Pro "Core 2 Duo" 2.66 13" (10)

64

64

32/64

MacBook Pro "Core i5" 2.4 15" (10)

64

64

32/64

MacBook Pro "Core i5" 2.53 15" (10)

64

64

32/64

MacBook Pro "Core i7" 2.66 15" (10)

64

64

32/64

MacBook Pro "Core i5" 2.63 17" (10)

64

64

32/64

Mac mini "Core Solo" 1.5

32

32

32

Mac mini "Core Duo" 1.66

32

32

32

Mac mini "Core Duo" 1.83

32

32

32

Mac mini "Core 2 Duo" 1.83

64

64

32*

Mac mini "Core 2 Duo" 2.0

64

64

32*

Mac mini "Core 2 Duo" 2.0 (Early 2009)

64

64

32*

Mac mini "Core 2 Duo" 2.26 (Late 2009)

64

64

32*

Mac mini "Core 2 Duo" 2.53 (Late 2009)

64

64

32*

Mac mini "Core 2 Duo" 2.53 (Server)

64

64

32*

Mac mini "Core 2 Duo" 2.4 (Mid-2010)

64

64

32/64

Mac mini "Core 2 Duo" 2.66 (Server)

64

64

64/32

Mac Pro "Quad Core" 2.66 (Original)

64

32

32

Mac Pro "Eight Core" 2.8 (2008)

64

64

32/64

Mac Pro "Quad Core" 2.66 (2009)

64

64

32/64

Mac Pro "Eight Core" 2.26 (2009)

64

64

32/64

Mac Pro "Quad Core" 2.8 (2010)

64

64

64/32

Mac Pro "Six Core" 3.33 (2010)

64

64

64/32

Mac Pro "Eight Core" 2.4 (2010)

64

64

64/32

Mac Pro "Twelve Core" 2.66 (2010)

64

64

64/32

Mac Pro "Quad Core" 2.8 (Server)

64

64

64/32

Mac Pro "Six Core" 3.33 (Server)

64

64

64/32

Xserve Xeon 2.0 "Quad Core"

64

32

32

Xserve Xeon 2.8 "Quad Core"

64

64

32/64

Xserve Xeon Nehalem 2.26 "Quad Core"

64

64

32/64

* These models are believed to be hardware capable of booting MacOS X 10.6 "Snow Leopard" in 64-bit mode, but it appears that they have been blocked in EFI from doing so. Unauthorized hacks are available.

To determine if your particular Mac has a 32-bit or 64-bit processor, 32-bit or 64-bit EFI, and whether or not your Mac is set to boot/running in 32-bit or 64-bit mode, an easy way is to download Startup Mode Selector. Please note that the author is providing this program as "donationware" and if you find the program useful, please contribute to his chosen charity.

If using this program on your Mac provides you with information that is different from what is provided above, please share so that the chart may be revised. Thank you.

Site sponsor PowerMax sells MacOS X 10.6 "Snow Leopard" as well as new and used Macs free of sales tax.

Also see:

  • Why does MacOS X 10.6 "Snow Leopard" boot in 32-bit mode by default? How can I boot in 64-bit mode? What are the advantages of 64-bit mode? Are there any disadvantages?
  • What is "OpenCL"? Which Macs support the "OpenCL" technology provided by MacOS X 10.6 "Snow Leopard"?
  • What is "Grand Central Dispatch"? Which Macs support the "Grand Central Dispatch" technology provided by MacOS X 10.6 "Snow Leopard"?

 


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