OS X build

[Cwfalconfootball]

im not sure if theres a better section for this. anyway here is my build: ASUS P8 Z68-V/GEN3 MOBO with intel core i5-3570k 1155 socket processor and msi radeon RX 580 4GB gpu. i have gotten the gpu to work ALONGSIDE the igpu of the motherboard but not without. Id like to get it to work alone because i have to switch my monitor every time i boot the computer. any ideas how i can fix this?

I use Clover boot loader.