Specifically, the following Macs are compatible with macOS Sierra. However, just because a Mac runs macOS Sierra does not mean that it is compatible with all features. IMac 'Core 2 Duo' 3.06 21.5'. IMac 'Core 2 Duo' 3.33 21.5'. The older macOS High Sierra had a little more scope. Apple said that would run happily on a late 2009 or later MacBook or iMac, or a 2010 or later MacBook Air, MacBook Pro, Mac mini or Mac Pro.

While the yearly major macOS update system is free to install, it is still limited to Macs that Apple deems compatible, and every year a generation of Macs essentially becomes obsolete. This is despite the fact that Apple is eager to emphasize that macOS is a widely compatible operating system.

As it happens, there are still people with close to ten-year-old Apple desktop computers still in use on a daily basis, likely performing a range of lighter tasks.

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Which Macs Don't Support High Sierra

For some reason Apple doesn't want to allow these Macs to run one of its latest operating systems, namely macOS 10.13 High Sierra. This leaves the following Macs on macOS 10.11 El Capitan:

  • MacBook Pro – late-2009 or earlier models
  • MacBook – late-2008 or earlier models
  • MacBook Air – 2009 or earlier models
  • iMac – late-2008 or earlier models
  • Mac Mini – 2009 or earlier models
  • Mac Pro – 2009 or earlier models.

Imac 2008 Sierra 7

These machines are considered obsolete and vintage by Apple. The company defines vintage products as those that have not been manufactured for more than five years but less than seven years ago. Obsolete products are those discontinued more than seven years ago.

How To Install macOS High Sierra on Unsupported Macs

Imac 2008 mac os sierra2008

Though Apple doesn't support the above hardware officially, someone has thought about sharing the love for these older machines. A developer known as DOSDude1 has written a patch that works on Macs with the Penryn architecture. Using this still imposes certain limitations, but at least makes it possible to install macOS High Sierra on the following Macs:

Imac

Imac 2008 Sierra Air

  • Early-2008 or newer Mac Pro, iMac, or MacBook Pro (MacPro 3,1 and 4,1, iMac 8,1 and 9,1, MacBook Pro 4,1, 5,1, 5,2, 5,3, 5,4, and 5,5).
  • Late-2008 or newer MacBook Air or Aluminum Unibody MacBook (MacBook Air 2,1, MacBook 5,1).
  • Early-2009 or newer Mac Mini or white MacBook (Mac Mini 3,1, MacBook 5,2)
  • Early-2008 or newer Xserve (Xserve 2,1, Xserve 3,1).
Air

If you happen to own any of the Penryn Macs mentioned above, the macOS High Sierra Patch Tool written by DOSDude1 will make running the latest software possible. But remember, with High Sierra you will also migrate to the Apple File System, and it is highly recommended that you first disable SIP because it may prevent the patch from working at all.

Installing the operating system on any of these Macs will require some technical knowledge, so it is not recommended for novice users. Also, a backup of your data is always a good idea in case anything goes wrong.

While there is a full step-by-step tutorial and video tutorial available on DOSDude1's website, it’s good to get a summary of the basics, which start with downloading the macOS High Sierra Installer app from the Mac App Store:

  1. Format a USB drive as Mac OS Extended (Journaled) via Disk Utility.
  2. Open the macOS High Sierra Patcher tool, navigate to the High Sierra Installer App, then select your pen drive and click “Start Operation”.
  3. Boot from the USB drive by holding down the option key after reboot.
  4. Install macOS normally, reboot back on the installer drive, and then open the “macOS Post Install” application.
  5. From the options, select the Mac model you own. This step is important, because it contains the optimal patch for that specific model.
  6. Click the “Patch” button, and after the process has finished, click “Reboot”.

The Reason Not To Install macOS High Sierra on an Unsupported Mac

Imac

As you may have already experienced with other types of officially unsupported machines, the probability of having issues is much higher. The same applies in this case, too, since the macOS High Sierra Patcher will render your iMac 8.1 Broadcom Wi-Fi chip useless for certain models.

Macs that use the Broadcom BCM4321 Wi-Fi module will not have functional Wi-Fi when running High Sierra. Another issue that has been highlighted by the developer is that the trackpad in the MacBook 5,2 isn't fully supported in this version of OS.

These are just a few of the possible issues that could arise, and this is before even mentioning the various potential software errors that you can run into by using out-of-date hardware. Without getting the proper knowledge beforehand, you'll need to revert back to the previous state of the Mac, which won't be an easy process, especially not without a Time Machine backup.

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