Can I Upgrade or Downgrade to OS X Snow Leopard (OS X 10.6)?

Snow Leopard Minimum Requirements

Apple Senior Vice President of OSX Software Bertrand Serlet delivers a keynote address on the new OSX Snow Leopard operating system.
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Can I upgrade or downgrade to Snow Leopard (OS X 10.6)?


OS X Snow Leopard is considered the last version of the operating system that was predominantly designed without major influences from iOS devices, such as the iPad and iPhone. As a result, it remains a highly desirable version of OS X, and is still available from Apple as a direct purchase from the Apple web site.

The reason Apple still sells OS X Snow Leopard is because it's the first version of OS X that includes support for the Mac App Store.

Once you install the OS, you can use the Mac App Store to update to any of the later versions of OS X, as well as purchase and install many apps for OS X.

Let's take the upgrade or downgrade question as two separate inquiries. We'll start with upgrading to Snow Leopard from a Mac running an earlier version of OS X.

We'll tackle the downgrade question a bit later in this guide.

Can I Upgrade?

The quick and dirty answer is, if your Mac uses an Intel processor then you can upgrade to OS X 10.6 (Snow Leopard). However, there's much more you should know before you make a final decision.

Which Mac Do You Have and What Processor Does It Use?

Before you can decide whether you should upgrade to Snow Leopard, you need to know which Mac and processor you have. To find out, you can use Apple’s System Profiler.

  1. From the Apple Menu, select About This Mac.
  2. Click the More Info… button, or the System Report button, depending on the version of OS X you're using.
  1. In the System Profiler window that opens (the actual window name will be your computer’s name), make sure that the Hardware category is selected from the Contents list on the left. Only the word Hardware should be selected; none of the Hardware sub-categories should be selected.

    Make note of the following:

    • Model Name
    • Processor Name
    • Number of Processors
    • Total Number of Cores
    • Memory
  1. Click the Graphics/Displays sub-category, located under the Hardware category.

    Make note of the following:

    • Chipset Model
    • VRAM (Total)

Minimum Requirements

Let’s start by determining whether your Mac meets the minimum configuration requirements for OS X 10.6 (Snow Leopard).

  • Snow Leopard will only run on Macs that have Intel processors. If the Processor Name includes the words PowerPC, your Mac isn’t capable of running Snow Leopard. In order to run Snow Leopard, the Processor Name must include the word Intel.
  • You also need at least 1 GB of memory, but since Intel Macs ship with at least 1 GB of memory, if you have an Intel Mac, you don’t need to worry about Snow Leopard’s minimum memory requirements.

64-bit and Grand Central Dispatch

Even if your Mac meets the minimum requirements for running Snow Leopard, that doesn’t necessarily mean it will be able to use all of the new features included in Snow Leopard.

The one thing that will make the most difference in how well Snow Leopard performs on your Mac is whether your Mac supports 64-bit architecture and can therefore run the Grand Central Dispatch technology built into Snow Leopard.

64-bit support requires a Mac’s processor(s) to support a 64-bit architecture.

Just because the Processor Name has the word Intel in it doesn't guarantee the processor supports a 64-bit OS like Snow Leopard.

When Apple first introduced the Intel architecture it used two processor types: Core Solo and Core Duo (Core Duo is not the same as Core 2 Duo). Core Solo and Core Duo both use 32-bit Intel processors. If your Processor Name includes the terms Core Solo or Core Duo, then your Mac will not be able to run in 64-bit mode or take advantage of Grand Central Dispatch.

Any other Intel processor that Apple has used has a full 64-bit architecture. In addition to fully supporting Snow Leopard, the 64-bit processor architecture also provides direct benefits, including speed, larger RAM space, and better security.

Grand Central Dispatch allows Snow Leopard to divvy up processes across multiple processors or processor cores, which will significantly improve the performance of your Mac. Of course, in order to take advantage of this technology, your Mac must have multiple processors or processor cores. You can see how many processors or processor cores your Mac has by clicking the Hardware category and looking at the Number of Processors and Total Number of Cores on the right side of the window. The more the merrier!

Even if your Mac can’t run in 64-bit mode and use Grand Central Dispatch, Snow Leopard will still provide a modest performance boost because it's optimized for the Intel architecture, and has all of the old legacy code stripped out of it.


OpenCL is one of the features built into Snow Leopard. In essence, OpenCL allows applications to take advantage of a graphics chip’s processor, just as if it were another processor core in the Mac. This has the potential to provide vast increases in performance, at least for specialized applications such as CAD, CAM, image manipulation, and multimedia processing. Even routine applications, such as photo editors and image organizers, should be able to increase overall capabilities or performance using OpenCL technologies.

In order for Snow Leopard to use OpenCL your Mac must use a supported graphics chipset. Apple lists the supported graphics chipsets as:

  • ATI Radeon 4850
  • ATI Radeon 4870
  • NVIDIA GeForce 9600M GT
  • NVIDIA 8800 GT
  • NVIDIA 8800 GTS
  • NVIDIA 9400M
  • NVIDIA 9600M GT
  • NVIDIA GT 120
  • NVIDIA GT 130

If the Chipset Model value in the Graphics/Displays subcategory (under the Hardware category) doesn’t match one of the above names, then your Mac currently cannot use the OpenCL technology in Snow Leopard.

Why do I say currently? Because this list is in flux. It represents the graphics chips that Apple has tested, not all the graphics chips that are capable of supporting OpenCL. For instance, both ATI and NVIDIA have older graphics cards and chipsets that are capable of supporting OpenCL, but it will require someone to produce an updated driver for the Mac to make them work.

A special note for Mac Pro users: Early Mac Pros from 2006 shipped with PCI Express v1.1 slots. All OpenGL-compatible graphics cards need PCI Express slots v2.0 or later. So, while you may be able to swap an OpenCL-compatible graphics card into your early Mac Pro and have it run effectively as a standard graphics card, it may have performance issues when it attempts to use OpenCL. For this reason, I consider Mac Pros sold before January 2007 unable to run OpenCL.

Snow Leopard and Your Mac

To wrap things up, Snow Leopard will only run on Intel-based Macs that have least 1 GB of RAM installed.

Intel-based Macs that have a 64-bit processor architecture will enjoy even better performance with Snow Leopard, because of their ability to run two of Snow Leopard’s core new features: Grand Central Dispatch, and the memory space, speed, and security that 64-bit brings.

If you have a 64-bit Intel Mac with a supported graphics chipset, you’ll enjoy additional performance improvements via the OpenCL technology, which allows a Mac to use the graphics processors as computational processors when they’re not busy doing other things.

Can I Downgrade to Snow Leopard?

The general answer is no. The reason is that Macs Apple produced after the next version of OS X (OS X Lion) was released may have hardware that requires specific drivers or initialization processes that were never included in OS X Snow Leopard.

Without the necessary code, your Mac is likely to fail to start up, fail the install process, or crash, if for some reason you were able to successfully complete the installation.

However, if you're thinking about downgrading a Mac that currently runs a newer version of OS X than Snow Leopard, and the Mac in question originally came equipped with OS X Snow Leopard or earlier, then yes, you can downgrade to OS X Snow Leopard.

Be aware, however, that the process will require you to erase your startup drive, and lose all your current data, so be sure to back up your Mac before proceeding. In addition, there's no guarantee that any user data that was created with a version of OS X that post-dates Snow Leopard will be usable with Snow Leopard or the apps that created them.

Now, in many cases your user data will be transferable. For example, a photo in any of the standard image formats should work just fine under Snow Leopard, but your Apple Mail messages may not be readable by the Snow Leopard version of Mail, because Apple changed message formats in some of the later versions of OS X. This is, of course, just one example of the type of issues that may surface when downgrading from one version of OS X to a previous version.

If you’re willing to try the downgrade process, you can do so using the Clean Install of Snow Leopard OS X 10.6. Remember, this will erase all of the data on your startup drive, so let me repeat: have a full, current backup of your data before beginning the downgrade process

Published: 8/8/2009

Updated: 12/2/2015

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