Hi, I've an AMD 6850 on Mojave and it work. Install the kext AMDController6000.kext, AMDLegacyFramebuffer.kext, AMDLegacySupport.kext with Kextwizard in System/Library/Extension, repair the permits and reboot.
With this process I've only a little problem with the animation.
It is because Mojave does not support Radeon HD6000 series.
tested my old HD 7770 card on Mojave
AMD Radeon HD 7770: Chipset Model: AMD Radeon HD 7770 Type: GPU Bus: PCIe PCIe Lane Width: x16 VRAM (Dynamic, Max): 1024 MB Vendor: AMD (0x1002) Device ID: 0x683d Revision ID: 0x0000 Metal: Supported Displays:
Hi there, I have been pulling my hair out trying to make this Radeon HD 7770 card work on Mojave. Curious what KEXT files you are using? I have been getting a display from Whatevergreen and I get mirrored dual display at 1024x768 using a kext I found called AppleGraphicsHD7750.kext.
I would love any advice getting this Radeon to work would be helpful since you seem to have this card running.