Step 1

You need to first disable System Integrity Protection (SIP) from the Recovery volume.

Start the computer and keep holding Option key (ALT on Windows keyboards) until you see a boot selector.

Choose Recovery volume from it (macOS version number doesn't matter).

Step 2

Click Utilities from top bar, then choose Terminal.

Step 3

Type csrutil disable and press ENTER.

Step 4

Click Apple logo from the top bar and choose Restart to reboot the computer in normal mode.

Step 5

Click Apple logo from the top bar and choose About this Mac, then click System report button.

Click Software from the list and ensure that System integrity protection is in Disabled state.

Step 6

Download and run Kext Utility from the following website: http://cvad-mac.narod.ru/index/0-4

You might see a warning that it cannot be opened.

Step 7

Click Apple logo from the top bar and choose System preferences.

Then click Security & Privacy icon.

Step 8

Click Open Anyway button to launch the program.

Step 9

Enter your username and password and press OK button.

Step 10

Upon launching Kext Utility wait until it rebuilds permissions and update caches.

Step 11

Download and unpack Lilu.kext to the desktop: https://github.com/acidanthera/Lilu/releases/download/1.2.7/1.2.7.RELEASE.zip

Drag and drop Lilu.kext over Kext Utility window to install it.

Step 12

Download and unpack AppleALC.kext to the desktop: https://github.com/acidanthera/AppleALC/releases/download/1.3.2/1.3.2.RELEASE.zip

Drag and drop AppleALC.kext over Kext Utility window to install it.

Click Apple logo from the top bar and choose Restart to reboot the computer.

Step 13

Upon reboot click Apple logo from the top bar again and choose About this Mac, then click System report button.

Click PCI from the list and ensure that macOS reports Driver installed: Yes for Audio Controller which is the same slot as your graphics card.

Close System report window.

Step 14

Click Apple logo from the top bar once again and choose System preferences.

Then click Sound icon.

Step 15

Click Output tab. You should now see your HDMI audio or DisplayPort audio device on the list. Make sure it's selected to have sound.