How to fix
Install MacOS High Sierra on an older Mac
on Windows

Hi. I have a Mac from early 2008. Could you show me how to install MacOS High Sierra? Or is it impossible?

You can install MacOS High Sierra on an older Mac. However, there are specific requirements, and not all older Mac devices can be "hacked" that way. Additionally, note that there are high risks since performing such actions goes against Apple's advice. Likewise, weigh the advantages and disadvantages before proceeding.

If you have still decided to install MacOS High Sierra on an older Mac, you will need several things before you can start. First of all, get a USB drive[ref en-1] with at least of 8 GB of free space and download MacOS High Sierra Patcher. Later, get a copy of MacOS High Sierra, and you are able to start the procedure. 

You can install MacOS High Sierra on the following devices:

• Early-2008 or newer iMac, Mac Pro, or MacBook Pro;
• Early-2008 or newer Xserve;
• Late-2008 or newer Aluminum Unibody MacBook or MacBook Air;
• Early-2009 or newer white MacBook or Mac Mini.

Unfortunately, but this hack won't work on the following Mac computers:

• 2006-2007 Mac Pros, MacBook Pros, iMacs, and Mac Minis;
• 2006-2008 MacBooks;
• 2007 iMac 7,1 (If you have updated the CPU to Penryn-based Core 2 Duo);
• 2008 MacBook Air.

Learn how to install MacOS High Sierra on an older Mac

Before you start the procedure, it is important to make sure that SIP[ref en-2] is disabled. If you are not sure whether it is disabled or it re-enables use the following instructions to fix this issue:

1. Click on the Apple's icon and select Restart;
2. While the computer is still restarting hold Command + R to reboot your Mac into Recovery System;
3. Open Terminal and type csrutil disable;
4. Press Return.

Also, it is wise to store backups[ref en-3] in case you encounter any damage to your system. If you store them in the cloud or an external drive, they will be safe, and you will avoid any data loss. 

Step 1. Prepare your USB drive

1. Insert the USB drive;
2. Open Disk Utility.
   

   

   
   
3. Pick OS X Extended (Journaled) and format it.

Step 2. Use MacOS High Sierra Patcher

1. Open MacOS High Sierra Patcher;
2. Search for the copy of MacOS High Sierra Installer and open it.
   

   

3. Wait for the Patcher to verify it;
4. In the right-bottom corner select your USB drive;
5. Press Start Operation.
   

   

   
   
6. After the operation is completed, turn your Mac on while holding the Option key;
7. Select your USB drive once the Mac is on.

Step 3. Install Mac OS High Sierra

1. Install MacOS normally and boot back into the installer drive;
2. Open MacOS Post Install application;
3. Select the model of Mac you are using and on which volume you have installed MacOS High Sierra on;
4. Click Patch and once it is finished press Reboot.