You should only disable the Intel HD 4000 in the bios if you are using a SMBIOS that doesn't have an IGPU, i.e. Mac Pro or iMac Pro SMBIOS.
If you are using an iMac SMBIOS, the system will be expecting an IGPU to be present, while it might only be used for limited processes it is an integral part of the OS/workings. Apple uses the IGPU for QuickSync and compute tasks in their iMac systems.
If you are using Lilu.kext and WhateverGreen.kext you should not be using any of the following:
- Remove (if used previously) these kexts:
— IntelGraphicsFixup.kext
— NvidiaGraphicsFixup.kext
— CoreDisplayFixup.kext
— Shiki.kext
— IntelGraphicsDVMTFixup.kext
— AzulPatcher4600.kext
— AppleBacklightFixup.kext,
— FakePCIID_Intel_HD_Graphics.kext
— FakePCIID_Intel_HDMI_Audio.kext
— and FakePCIID.kext (if there are no other FakePCIID plugins)
- Turn off all Clover's graphic injects for Intel, ATI and Nvidia.
- Turn off Clover's DSDT fixes:
— AddHDMI
— FixDisplay
— FixIntelGfx
— AddIMEI
— FixHDA
- Turn off Clover's UseIntelHDMI.
- Delete -disablegfxfirmware and -igfxnohdmi boot arguments.
- Delete Clover's FakeID for IntelGFX and IMEI.
- Delete Clover's ig-platform-id.
- Completely remove Clover's Arbitrary, AddProperties, as well as IGPU, IMEI, HDEF and HDMI audio definitions from SSDT and DSDT (if you added them).
- Delete or disable binary patches DSDT: GFX0 to IGPU, PEGP to GFX0, HECI to IMEI, MEI to IMEI, HDAS to HDEF, B0D3 to HDAU.
- Delete the framebuffer name (Orinoco) from your config, or any patches you may have applied.
All of these items are dealt with by WhateverGreen.kext.
Only these properties should be added to your config:
— AAPL,ig-platform-id or for Sandy Bridge IGPU - AAPL,snb-platform-id framebuffer
— device-id for IGPU (if faking is necessary)
— device-id for IMEI (if faking is necessary)
— properties for patches (if necessary)
The above details have been taken from Acidanthera's WhateverGreen FAQ IntelHD manual, which can be found here -
https://github.com/acidanthera/WhateverGreen/blob/master/Manual/FAQ.IntelHD.en.md
Regarding the DisplayPort to DVI cables, make sure you can return them, in case they don't work. I personally would go with the DisplayPort to HDMI cable/adapter., if the two displays have HDMI connections. You should be aware that these cables/adapters are fairly delicate and don't like being moved around a lot. They can be damaged quite easily if mishandled. I know this from first hand experience, as my son and his Uni housemates were forever damaging his cables and adapters. I lost count of how many I bought him.
Regarding the SSDT-RX580. Does this contain the correct ACPI address for your RX580? Look in your IOReg and see what ACPI path your RX 580 uses and see if it corresponds with the ACPI path in the SSDT. If not you need to disassemble the SSDT-RX580, i.e use terminal command to disassemble the SSDT and save it as SSDT-RX580.dsl. There will be a guide on this site on how to disassemble the SSDT. Once it has been disassembled you can edit the ACPI path, you can then save it with the new path, before saving it as an Assembled Machine Language binary (SSDT-RX580v2.aml) file.
The screenshot below show the ACPI Path for my RX580 - IOACPIPlane:/_SB/PCI0@0/PEG0@10000/PEGP@0
If matched in the SSDT-RX580 it would be shown as (_SB.PCI0.PEG0.PEGP)
As you have an XFX RX580 dGPU it is highly likely you will run in to a framebuffer issue. XFX were and probably still are notorious for placing custom VBIOS's in their cards. These custom VBIOS's don't match with the Framebuffer properties provided in the kexts as part of macOS by Apple. So it is sometimes necessary to create a custom framebuffer for your XFX dGPU. Again there are plenty of threads here showing how to accomplish this, if it is necessary. You won't know till you have tried using the DP-DVI or DP-HDMI adapters/cables.
Lots for you to do and think about.