I have rebuilt my AMD Sabertooth FX990 / FX 8320 / RX 580 system on a test frame to check out the black screen issues you ran into and can confirm the following:
- Big Sur fully supports the RX 580 / 590 dGPU, as the Polaris drivers don’t require the AVX2.0 CPU Instruction Set.
- When Apple dropped the Mac Pro 6,1 system with the release of Monterey all of their supported systems included the AVX2.0 Instruction Set (Haswell or newer systems).
- Apple changed the Polaris, Vega and Navi GPU drivers in Monterey and newer so they have to work with AVX2.0.
- The old AMD Piledriver and Bulldozer (FX AM3+) systems lack the AVX2.0 Instruction Set, so when running Monterey or newer there is no graphics acceleration and commonly when booting ends on a black screen instead of the macOS login screen or desktop.
- I have installed Big Sur, Monterey and Ventura on a 240GB SSD (3 x 80GB partitions set as APFS)
- Big Sur works as expected with full graphics acceleration.
- Monterey and Ventura both boot to a black screen.
The fix for the black screen issue is as follows:
- Add the latest version of CryptexFixup.kext to your bootloaders kext folder and config.plist.
- https://github.com/acidanthera/CryptexFixup
- Add -amd_no_dgpu_accel boot argument to your config.plist.
- This boot argument will boot the system with the AMD GPU disabled, temporarily getting around the black screen issue.
- Then download and install OpenCore Legacy Patcher (OCLP) on your Bulldozer system running Monterey or Ventura.
- You will need to add AMFIPass.kext to your bootloader’s kext folder, to enable OCLP to run the Polaris and USB1.1 Root Patches.
- You will need to remove the amd_no_dgpu_accel boot argument before rebooting the system.
- This will allow graphics acceleration for your RX 590 when you next boot in to the system.
Just for clarification I used the above process to get graphics acceleration working in Ventura.
For some reason the OCLP Polaris and USB1.1 Root Patches that were offered in Ventura weren’t available in Monterey. I am not sure if this was an issue with my Monterey installation or the EFI amendments listed above, which worked for Ventura.
As with most hacks for systems that are lacking a specific instruction set, there will still be some graphical glitches and artefacts in Ventura.