RX 6600 Dual Monitor Issue

[MrCabana]

Hello everyone,

I recently bought a new MSI RX 6600 Mech 2x dGPU to replace my Intel's iGPU. Performed a clean install of Ventura which works fine, except for the dual Display now.

This GPU has 4 output ports:

1) (right next to screw) DP -> to my main monitor using a DP=>HDMI connector

2) HDMI -> to my second monitor using HDMI cable

3) DP -> empty

4) DP -> empty

Problem is that in BIOS, only the first monitor (DP) works. After that, OC starts to load Ventura and about 1/4 of the way, both monitors go blank and then only the second monitor (HDMI) emerges. If I re-plug the DP adapter, both monitors come to life.

Curiously, the same thing happens on Windows. I don't want to mess with windows right now because I installed AMD drivers on top of previously used Intel's iGPU. Maybe it's just a driver issue that will be fixed when I have the chance to clean install Windows in a few weeks. Yes, I tried loading Windows through OC and also through its own UEFI entry in BIOS. Same result.

Another curiosity, after messing with it, I managed to get both displays working on Ventura and Windows. Basically, I re-plugged DP in windows, changed both displays frame rates a few times and rebooted into Ventura. It survived several reboots. But then, I started dealing with USB port mapping. Changed a few things in my config.plist and added USBPort.kext and USBInjectAll.kext. Now my USB ports are perfect, but the dual display on boot is gone.

I've tried several combinations, including using a DP=>DVI adapter, which gave me the two monitors working at BIOS, but same mono display on Ventura and Windows.

Unfortunately, I don't have a monitor with DP input to try a straight cable without the DP=>HDMI adapter.

I don't think it's a problem with the monitors, the cables, the adapter or even the GPU ports. All of them work fine if I re-plug DP. It seems to be some detection issue with the drivers.

Right now I'm pulling my hair off with this. I bought this GPU because I heard it should work OOB with hackintoshes.

I appreciate if anyone could shed some light into this. Thanks in advance.

My specs:

Mobo: Asus TUF Gaming-Plus with Wi-Fi

Proc: Intel i3 10100 (with iGPU disabled in BIOS)

Memory: 2x16 2666mhz DDR4

GPU: MSI RX 6600 Mech 2x

 

 

[MaLd0n]

check if csm is disabled on bios/uefi setup

[MrCabana]

Hello MaLd0n.
Yes, it's disabled.

[MrCabana]

I don't know if it helps, but I took IOReg screen shots before and after re-plugging the DP adapter.

IOReg Screenshots.zip

[MrCabana]

UPDATE:

For anyone reading this ... apparently the problem is solved by replacing the HDMI cable that was connected to the adapter.

I had 3 spare cables here and I had tried them all. Then I decided to borrow other 10+ cables from a friend. First attempt and BANG! It works. It's a thicker one, maybe supporting a later version of HDMI that made it work.

Now I replaced the old cables with two new ones and it's all working flawlessly and, so far, this setup survived after 5 reboots.