I would start with an sbios update is possible.
I swapped out the ASRockRack X470D4U mobo for a new, next-gen X570D4U. Keeping the same 2X16GB UDIMMs, and trying 2 different Ryzen 5600G CPUs, I now see the following ... With an NVIDIA PCIe card as primary adapter, it posts & functions, as before; no issues or problems. Selecting the on-die AMDGPU, via the board's HDMI connector, now also posts & boots; No more OOPS. Booting, now on uname -rm 5.14.14-200.fc34.x86_64 x86_64 dmesg @ boot is: dmesg | grep -i amdgpu [ 1.623977] [drm] amdgpu kernel modesetting enabled. [ 1.627731] amdgpu: Virtual CRAT table created for CPU [ 1.627738] amdgpu: Topology: Add CPU node [ 1.627782] fb0: switching to amdgpudrmfb from EFI VGA [ 1.627910] amdgpu 0000:30:00.0: vgaarb: deactivate vga console [ 1.627972] amdgpu 0000:30:00.0: amdgpu: Trusted Memory Zone (TMZ) feature enabled [ 1.634655] amdgpu 0000:30:00.0: amdgpu: Fetched VBIOS from ROM BAR [ 1.634656] amdgpu: ATOM BIOS: 113-CEZANNE-018 [ 1.635463] amdgpu 0000:30:00.0: amdgpu: VRAM: 512M 0x000000F400000000 - 0x000000F41FFFFFFF (512M used) [ 1.635465] amdgpu 0000:30:00.0: amdgpu: GART: 1024M 0x0000000000000000 - 0x000000003FFFFFFF [ 1.635466] amdgpu 0000:30:00.0: amdgpu: AGP: 267419648M 0x000000F800000000 - 0x0000FFFFFFFFFFFF [ 1.635504] [drm] amdgpu: 512M of VRAM memory ready [ 1.635505] [drm] amdgpu: 3072M of GTT memory ready. [ 1.639127] amdgpu 0000:30:00.0: amdgpu: PSP runtime database doesn't exist [ 1.667936] amdgpu 0000:30:00.0: amdgpu: Will use PSP to load VCN firmware [ 2.469604] amdgpu 0000:30:00.0: amdgpu: RAS: optional ras ta ucode is not available [ 2.477996] amdgpu 0000:30:00.0: amdgpu: RAP: optional rap ta ucode is not available [ 2.477999] amdgpu 0000:30:00.0: amdgpu: SECUREDISPLAY: securedisplay ta ucode is not available [ 2.478948] amdgpu 0000:30:00.0: amdgpu: SMU is initialized successfully! [ 2.530805] kfd kfd: amdgpu: Allocated 3969056 bytes on gart [ 2.758719] amdgpu: HMM registered 512MB device memory [ 2.758741] amdgpu: SRAT table not found [ 2.758741] amdgpu: Virtual CRAT table created for GPU [ 2.758942] amdgpu: Topology: Add dGPU node [0x1638:0x1002] [ 2.758944] kfd kfd: amdgpu: added device 1002:1638 [ 2.758958] amdgpu 0000:30:00.0: amdgpu: SE 1, SH per SE 2, CU per SH 18, active_cu_number 27 [ 2.949242] fbcon: amdgpu (fb0) is primary device [ 3.052240] amdgpu 0000:30:00.0: [drm] fb0: amdgpu frame buffer device [ 3.061026] amdgpu 0000:30:00.0: amdgpu: ring gfx uses VM inv eng 0 on hub 0 [ 3.061030] amdgpu 0000:30:00.0: amdgpu: ring comp_1.0.0 uses VM inv eng 1 on hub 0 [ 3.061031] amdgpu 0000:30:00.0: amdgpu: ring comp_1.1.0 uses VM inv eng 4 on hub 0 [ 3.061032] amdgpu 0000:30:00.0: amdgpu: ring comp_1.2.0 uses VM inv eng 5 on hub 0 [ 3.061032] amdgpu 0000:30:00.0: amdgpu: ring comp_1.3.0 uses VM inv eng 6 on hub 0 [ 3.061033] amdgpu 0000:30:00.0: amdgpu: ring comp_1.0.1 uses VM inv eng 7 on hub 0 [ 3.061034] amdgpu 0000:30:00.0: amdgpu: ring comp_1.1.1 uses VM inv eng 8 on hub 0 [ 3.061034] amdgpu 0000:30:00.0: amdgpu: ring comp_1.2.1 uses VM inv eng 9 on hub 0 [ 3.061035] amdgpu 0000:30:00.0: amdgpu: ring comp_1.3.1 uses VM inv eng 10 on hub 0 [ 3.061036] amdgpu 0000:30:00.0: amdgpu: ring kiq_2.1.0 uses VM inv eng 11 on hub 0 [ 3.061037] amdgpu 0000:30:00.0: amdgpu: ring sdma0 uses VM inv eng 0 on hub 1 [ 3.061038] amdgpu 0000:30:00.0: amdgpu: ring vcn_dec uses VM inv eng 1 on hub 1 [ 3.061039] amdgpu 0000:30:00.0: amdgpu: ring vcn_enc0 uses VM inv eng 4 on hub 1 [ 3.061039] amdgpu 0000:30:00.0: amdgpu: ring vcn_enc1 uses VM inv eng 5 on hub 1 [ 3.061040] amdgpu 0000:30:00.0: amdgpu: ring jpeg_dec uses VM inv eng 6 on hub 1 [ 3.209226] [drm] Initialized amdgpu 3.42.0 20150101 for 0000:30:00.0 on minor 0 [ 13.749477] snd_hda_intel 0000:30:00.1: bound 0000:30:00.0 (ops amdgpu_dm_audio_component_bind_ops [amdgpu]) However, now, the output color registration is wrong. After grub selection, boot shell background is pink/magenta everywhere. Screenshot here: https://imgur.com/q2JJ4n6 If I continue from shell to launch a desktop environment (XFCE or KDE), it reaches runlevel 5 with no problems or errors -- EXCEPT the color registration is still wrong. Switching back to the NVIdia cures the issue - back to normal black background @ runlevel 3 shell, and correct colors @ rl5 The mv from X470D4U -> X570D4U apparently 'fixed' the problem with NO video output from the on-die GPU. BIOS, or other board issues, I'm not clear. Is this color issue *still* likely a BIOS issue? or the amdgpu driver?
