macOS Sierra Patcher Tool for Unsupported Macs
*This utility is provided to
anyone free of charge, however if you'd like to donate, you can do so
here:
Questions or comments? Feel free to contact me at collinmistr@gmail.com
Requirements:
-Early-2008 or newer Mac Pro, iMac, or MacBook Pro
-Late-2008 or newer MacBook Air or Aluminum Unibody MacBook
-Early-2009 or newer Mac Mini or white MacBook
-Early-2008 or newer Xserve
Things you'll need:
-A copy of the macOS Sierra Installer
App. This can be obtained from the Mac App Store either using a machine
that
supports Sierra, or you can use the "Download macOS Sierra" option in
the tool to download it from the App Store on your unsupported machine.
Just select Tools>Download macOS Sierra in the menu bar.
Alternatively, you can download a copy here

-A USB drive that's at least 8 GB in size
-A copy of the tool - Download here (Current version: 4.1.2)
Known issues:
-Unsupported WiFi modules in some
systems. Macs that use the Broadcom BCM4321 WiFi module will not have
functional WiFi when running Sierra. A fix for this is to open up your
machine and install a compatible WiFi card. Machines affected include
some MacPro3,1, MacBook5,2, MacBookPro4,1, iMac8,1, Macmini3,1, and
MacBookAir2,1 systems. Please note that not all these machines will
have an unsupported card, this is just a list of machines known to have
shipped with that card in some configurations.
*You can find out whether or not you have an unsupported card by
opening System Profiler (About this Mac>System Report...), and
clicking on WiFi under the Network section. If your card type reads
"(0x14E4, 0x8C)" or "(0x14E4, 0x9D)", then you do NOT have a compatible card. Any other
combination, such as (0x14E4, 0x8D), is a supported card.

-Trackpad (MacBook5,2 affected only). The trackpad in the MacBook5,2
isn't fully supported in Sierra. While it works and is fully usable,
Sierra detects it as just a standard mouse, preventing you from
changing some trackpad-oriented settings.
-Audio issue (iMac8,1 affected only). On some iMac8,1 systems, the
audio volume doesn't seem to change even when the system indicates that
it is. The audio is still usable, however it will remain at maximum
volume all the time.
How to use:
1. Insert your desired USB drive, open
Disk Utility, and format it as Mac OS Extended (Journaled).

2. Open the "macOS Sierra Patcher" tool, and browse for your copy of
the macOS Sierra Installer App.

*Ensure that the tool successfully verifies the app.

3. Next, select your USB drive in the Target Volume list, and click
"Start Operation."

4. When the operation completes, boot your target unsupported Mac off
the USB drive you just created.

Note: Only perform steps 5 and 6 if you intend to do a clean install.
Otherwise, you can simply skip these steps and install to your volume
containg a previous version of OS X, and it'll do an in-place upgrade.
5. When the installer boots, open Disk Utility.

6. Select the disk or partition you want to install on, and erase it,
ensuring to use Mac OS Extended (Journaled) as the filesystem type. If
formatting an entire drive, ensure GUID is selected.

7. Install macOS normally on the volume you just erased.

8. When the install completes, reboot back onto the installer drive.
This time, open the "macOS Post Install" application.

9. In the application, select the Mac model you are using. The optimal
patches will be selected for you based on the model you select. You can
also select other patches of your choosing.

10. Select the volume you have just installed macOS Sierra on, and
click "Patch." When it finishes patching, click "Reboot". It may sit
there for a few moments rebuilding caches before rebooting.
*If for some
reason the system fails to work correctly after rebooting, boot back
into your installer drive, run the post install patch again, and select
"Force Cache Rebuild" before rebooting. This isn't necessary under most
circumstances.

11. When it reboots, it should now boot into a fully working copy of
macOS Sierra.
