Ryzen 9800X3D + X870E + RX 6900 XT + RTX 5090 dual-GPU hackintosh — build log and current problem

[mrt360]

Goal​

I'm consolidating a separate Intel Hackintosh and Windows gaming PC into a single dual-boot workstation.

macOS -> RX 6900 XT only
Windows -> RTX 5090 + RX 6900 XT

The RTX 5090 does not need to function in macOS. Ideally macOS would not even enumerate it.

Hardware​

CPU: Ryzen 7 9800X3D
Motherboard: Gigabyte X870E AORUS Elite WiFi7
GPU (macOS): XFX RX 6900 XT
GPU (Windows): Zotac RTX 5090 (this plan is to deactivate in Mac OS)
NIC: Intel I226-V PCIe (AppleIGC)
PSU: be quiet! Dark Power Pro 13 1600W
Case: Lian Li O11 Dynamic EVO XL

Current layout:
• RTX 5090 horizontal in Slot 1
• RX 6900 XT upright using the EVO XL upright GPU kit (Slot 3 connection)

OpenCore​

OpenCore 1.0.7
SMBIOS: MacPro7,1

Kexts:
Lilu, VirtualSMC, WhateverGreen, AppleALC, AppleIGC, AMFIPass, RestrictEvents, AppleMCEReporterDisabler, NVMeFix, USBMap

Boot Args:
-v keepsyms=1 debug=0x100 agdpmod=pikera alcid=11 npci=0x2000 dart=0

What Works​

With only the RX 6900 XT installed:
• Sonoma boots reliably
• Photoshop 32-bit HDR confirmed working
• USB fully mapped
• Apple ID / iCloud working
• Intel I226-V is en0 with IOBuiltin=Yes
• Windows boots independently via BIOS F12 → Windows Boot Manager
• LSI 9211-8i HBA working correctly

The machine is completely stable in this configuration.

The Problem​

As soon as the RTX 5090 is installed and powered:

• BIOS output appears on the 5090
• OpenCore picker appears on the 5090
• Verbose boot appears on the 5090
• RX 6900 XT remains dark throughout the entire process

Boot then loops on:

AppleUserHIDDrivers
ITE Upgrade Mode(128)
VID:04D8 PID:57DB

Behaviour Matrix​

RX 6900 XT only → Boots normally

RTX 5090 installed and powered →
OpenCore displays on 5090
RX 6900 XT receives no signal
Infinite ITE / AppleUserHIDDrivers loop

RTX 5090 physically removed → Boots normally

RTX 5090 installed but power disconnected →
Gigabyte POST code 99
No POST

ACPI / PCI Mapping​

RTX 5090
01:00.0 → \SB.PCI0.GPP0.VGA
01:00.1 → \_SB.PCI0.GPP0.HDAU

RX 6900 XT
11:00.0 → \_SB.PCI0.GPP7.UP00.DP40.UP00.DP40.EP00

The two GPUs are on completely separate PCIe branches:
RTX 5090 → GPP0
RX 6900 XT → GPP7

Additional Investigation Already Performed​

OpenCore DeviceProperties

Attempted to disable the RTX 5090 using:
PciRoot(0x0)/Pci(0x1,0x1)/Pci(0x0,0x0)
disable-gpu = 01000000

Result:
• OpenCore still displayed on the RTX 5090
• Verbose boot still displayed on the RTX 5090
• RX 6900 XT remained dark
• Same ITE / AppleUserHIDDrivers loop

PCIe Slot Changes

Tested the RX 6900 XT in multiple slots.

Result:
• No change
• RTX 5090 remained the primary display device
• Same boot loop

Linux PCI / ACPI Investigation

Mapped PCI devices to ACPI paths under Ubuntu.

Confirmed:
RTX 5090 -> GPP0
RX 6900 XT -> GPP7

Behaviour With RTX 5090 Removed

• OpenCore boots normally
• RX 6900 XT becomes active
• Sonoma reaches desktop
• System remains stable

Behaviour With RTX 5090 Present

• GOP output transfers to the RTX 5090 before OpenCore loads
• OpenCore picker appears on the RTX 5090
• Verbose boot appears on the RTX 5090
• RX 6900 XT never receives a signal
• System enters the repeating ITE Upgrade Mode loop

Current Theory​

The issue may not be the NVIDIA display device itself, but something associated with the entire GPP0 branch.

Because:
5090 absent -> macOS works
5090 present -> macOS fails

DeviceProperties-based GPU disabling made no difference.

Questions​

• Has anyone successfully hidden or suppressed an RTX 50-series GPU from macOS on AM5 while keeping an AMD GPU active?
• Has anyone seen the repeating ITE Upgrade Mode / AppleUserHIDDrivers loop in a dual-GPU configuration?
• Has anyone used an SSDT to suppress an entire PCIe bridge (e.g. GPP0) under Darwin rather than disabling only the GPU function?
• Does GPP0 suppression sound like a sensible next avenue to investigate?

​

 

[Edhawk]

Honestly, combining both the GPUs in one system is going to cause you unnecessary problems. The Nvidia GPU will not play nicely if it is set as the main display out connection.

The best you can do is set the Nvidia GPU in the second PCIe slot, vertically using the x16 slot adapter. Have the AMD GPU in the first x16 slot and use a custom SSDT to disable the Nvidia GPU when you boot in to macOS.

The AMD card will not work correctly if the Nvidia card is set as the primary display out in the bios.

Keeping the two systems separate is not a bad thing, given the incompatibility of the Nvidia card.