did you know the RX580 sapphire works out of the box to get it to work just let the pc go to sleep and thin wake it up make sure all monitors are hooked
up before you boot up the system. let me know how it works for you. here is the specs of my machine
2 x 3.07 GHz 6-Core Intel Xeon
16 GB 1333 MHz DDR3
Radeon RX 580 8192 MB
2 monitors and a 60 inch samsung uhd tv
thank you all for reading my post I have ben working in apple products for years and hackintosh from the beginning .