I upgraded my MSI GTX770 lightning to a MSI RX480 GamingX (8gb) and it works like a charm !
* Did a fresh install of 10.12.2 using unibeast.
* Installed latest version of clover
* Modified clover's config.plist with following options
* ACPI: FixDisplay = true
* Devices: Fake ID - ATI - 0x67FF1002
* Graphics: Inject Intel and Inject AMD
* Reboot to bios, set IGPU primary (beware that you will be booting blind until OSX has been loaded, unless you connect a monitor to your internal graphics card)
Et voila, hardware accelerated OSX, no monitors connected to my iGPU, even the name is recognised in Sierra due to some recent patches in clover.
So, no need to patch the AMDRadeanX4100.kext, Fake ID let's the driver think you have have a compatible gpu installed.
Stability wise: GREAT! Been running for two days now and intensively using it for work, (dev, indesign and photoshop), Did a quick test with heaven, did not crash and 0 problems whatsoever. Sleep / resume is also working!
System: gigabyte z77-ds3h - intel i5 3570k - MSI RX480 GamingX
Hope this helps someone questioning if RX480 is working or not.
View attachment 225499