AMD RX Vega 56 multiple ports

[iLikeHackintosh]

How to get more than 2 display ports working on ROG Strix RX VEGA?

I get signal from DVI port and from one HDMi port. I do not have DisplayPort cables to test DP ports. Ports marked with green are working, but I would like to attach 3rd monitor into port marked with red, but no any image.

Any suggestions?

 

[Edhawk]

1. Do you know which Framebuffer your card uses?
2. Does it use the default Radeon, Iriri or Kamarang framebuffer?
3. Do you know the ACPI address of the Vega56?
4. IORegistryExplorer &/or Hackintool apps can be used to confirm the ACPI address and framebuffer in use.

You could try using one of the attached Vega 56 SSDT's to see if they help. They may need tweaking, if the ACPI address is not a match for (_SB.PCI0.PEG0.PEGP.LTRE), which both SSDT's use.

If you confirm the ACPI address for your card, I can edit the SSDT's to use the correct ACPI address.

Failing that you may need a custom framebuffer for your Vega 56, so both HDMI ports work.

My son uses a DisplayPort to HDMI cable (to connect to his TV) with his real MacBook Pro, maybe you could try something like that on your system. As the DP connections are more likely to be functional than the 2nd HDMI port.

 

[iLikeHackintosh]

@Edhawk, thank you for response.

Radeon RX Vega 56:

• Chipset Model: Radeon RX Vega 56
• Type: GPU
• Bus: PCIe
• PCIe Lane Width: x16
• VRAM (Total): 8 GB
• Vendor: AMD (0x1002)
• Device ID: 0x687f
• Revision ID: 0x00c3

03:00.0 1002 687F 1043 0555 Disabl Advanced Micro Devices, Inc. [ Vega 10 XL/XT [Radeon RX Vega 56/64] Display controller VGA compatible contr bridge@0/GFX0@0 display PciRoot(0x0)/Pci(0x1,0x0)/Pci(0x0,0x0)/Pci(0x0,0x0)/Pci(0x0,0x0)

 

[Edhawk]

Sorry I need to see the IOReg, as the ACPI name is truncated in Hackintool, i.e. the part containing /GFX0@0.

Read and follow this guide on how to create a copy of your IOReg, using a compatible version of the application, i.e. version 2.1 linked in the guide:

[Guide] How to Make a Copy of IOReg

IORegistryExplorer aka IOReg Apple Developer Tool Xcode How to Make a Copy of IOReg (Note 1) 1. IORegistryExplorer/File/Save a Copy As…. (no extension required) 2. Open file to verify (Note 2) 3. Attach to post (Note 3) Where To Get IOReg 1. Download Interim, link below Installation 1, Open...

www.tonymacx86.com

 

[iLikeHackintosh]

Seems that I have DisplayPort to DVI adapter and tested it, all DisplayPorts are working. Seems that I need DP to HDMI cable to get extra monitors to work. Seems that 2nd HDMi port is blank whatever I do.

 

[Edhawk]

That is not uncommon. I have an RX 580 which has three DP ports, but only two work. The DisplayPort to HDMI cables and adapters can be a bit flaky, while my son was at Uni I must have bought him 10 or more, as he and his housemates kept breaking them. If you plan to plug the cable in and leave it in place it should be fine. I think it was the repeated plugging in and removal that damaged the ends of the converter cable.


Ok, so according to your IOReg your RX Vega 56 currently uses the default Radeon Framebuffer.

The ACPI address for the card is (_SB.PCI0.PEG0.GFX0).

I have changed the ACPI address in both of the SSDT's attached, to match your setup. You can try each SSDT and these alternative Framebuffers, stated in the name of the SSDT's, separately to see if they help.

Add one of the SSDT's to your setup: (Iriri or Kamarang)

• If booting with OpenCore:
  • Add the SSDT to your /OC/ACPI folder &
  • Add an entry for the SSDT in your /OC/config.plist
• If booting with Clover:
  • Add the SSDDT to your /CLOVER/ACPI/patched folder

If the first doesn't work or make the changes you require, remove it and try booting with the other SSDT.

Hope this helps.