I found an open-box RX 480 8GB at Micro Center this morning and gave it a shot. Installed in my Mac Pro 5,1 which is running MacOS Beta 3, it can boot to the Desktop without any modification. I recall reading there's built-in driver for this GPU but ID is not matched. Anything I should try? Summary: RX 470 and RX 480 both work with acceleration and Metal support in macOS after adding PCI ID 0x67DF1002 to AMDRadeonX4100.kext. Other than no Boot Screen, you'll see UI during system update and in Recovery Mode. Kext editing needed after each OS update to reenable acceleration and Metal support. Update 1: Installed GM macOS Sierra build 16A319 today (9/8/16). While the RX 480 still works after the kext mod, OpenGL crashes remain an issue. The RX 470 on the other hand is fully functional without boot screen. Update 2: Installed 10.12.1 Beta tonight (9/21/16). Polaris support is definitely getting better. The Baffin personality which was in AMDRadeon4000.kext now has its own kext, AMDRadeon4100.kext. RX 480 is not crashing OpenGL apps anymore. This is the first time in nearly 2 months owning these RX 480 GPUs I was able to finish Unigine benchmarks. Update 3: I received PMs for instructions so I wrote this Mac Pro Radeon RX 480 How-to.