The card in question is the XFX 560 4 gigabyte model. DO NOT FLASH A 4GB BIOS ONTO A 2GB CARD! DO NOT USE THIS ON DIFFERENT MODEL!
- AMD/ATI ATIFlash - https://www.techpowerup.com/download/ati-atiflash/
- Sapphire RX 560 4GB BIOS (197766) - https://www.techpowerup.com/vgabios/197766/197766
2. Getting Ready
First, open GPU-Z and dump the original vbios from the card. Click the Arrow to the right of the "Bios Version" box and save it somewhere safe.
Next, extract ATIFlash to somewhere safe (I did it into Documents), then put the Sapphire vbios into the same directory.
Lastly, in Windows Explorer, click on the navigation bar on the top (Where it says "This PC > Documents") and type "cmd" to open a command prompt.
3. Flashing the Bios
Using the GUI for ATIFlash doesn't work. So, in the command prompt that you've opened, type
atiflash -p 0 -f 197766.rom
Press enter and you should see "Restart to finish flashing vbios" (or something similar to that). Restart your computer and open GPU-Z again. The subvendor should be "Sapphire" now, and MacOS will boot correctly.
4. Other Info
I booted into MacOS without any changes to clover, no InjectATI, no Deinit, no LoadVBios and no "-radoff". It should work fine.
Disclaimer: I'm not liable if you brick your card