Dual DisplayPort Monitors w/ RX 580

[mblum93]

Hi everyone,

I have a Mojave 10.14.6 build that works well. It has the following specs:

Mobo: ASUS ROG MAXIMUS XI HERO
Graphics: ASUS ROG Strix Radeon RX 580 O8G Gaming OC Edition

I just got a second Asus PB287Q monitor that I'd like to connect via DisplayPort. However, when I connect it via DisplayPort, it just flickers and shows a black screen. If I connect it via HDMI, the computer does not connect to the internet (WiFi or ethernet) on boot (if I connect the HDMI after the computer boots, it works fine, however the monitor's refresh rate is lower on HDMI so this isn't ideal either).

I've tried updating to the latest WhateverGreen and Lilu (versions 1.4.4 and 1.4.9, respectively), and I've tried changing my system definition to Mac Pro 6,1. Neither solution worked.

Any ideas would be appreciated!

Thank you,
Michael

 

[Edhawk]

Config.Plist:
You should be using the iMac 19.1 SMBIOS, with your components.

With the Mac Pro SMBIOS you would need to disable your IGPU, which seems a waste to me.

Using with a 'Headless' Intel framebuffer, so it can undertake QuickSync and other compute processes, like a real iMac, while the discrete card undertakes the main graphics processing is to me a better setup.

1. You have a boot argument that disables your IGPU, why?
2. You config.plist is missing the Devices > Properties settings required for your IGPU to work correctly.
3. You have Inject Intel=true set, which contradicts the processes undertaken by WhateverGreen.kext and is nonsense given the boot argument to disable the IGPU.
4. Your config is also lacking the RadeonDeInit=true setting, which your RX 580 requires.

There are other issues with your config, but they are not specifically graphics related.

Discrete Graphics Card:
Your ROG-STRIX-RX580-O8G-GAMING has the following connectors:

• 2 x Display Port
• 2 x HDMI
• 1 x DVI

If you use only one DisplayPort connection, say far right as you look at the image above, I assume it boots and works just fine, yes?

What happens when you use just the other DP connection, does it work or do you get the Black screen?

The HDMI connectors are unlikely to be configured correctly in the framebuffer you are using, via WhateverGreen.kext, due in part to the missing and incorrect config.plist settings mentioned above.

I have a dual monitor setup, using a pair of Dell U2515H screens, both connected via DP to a PowerColor RX 580 Red Devil GPU. My card has 3 x DisplayPort connections, but only two of them work. If I try to use the connector furthest to the right then I get the black screen issue on one of the displays. If I use the middle two DP connectors then both screens work perfectly. What this tells me is the DP port providing the Black Screen is not confirgured correctly in the Framebuffer. This is the same for your GPU, but unfortunately you only have two DP connections to start.

So you need to confirm, using IORegistryExplorer, which connectors the two DisplayPort connectors use. You can then either create a custom framebuffer or add a patch to your config.plist to try to get the two ports configured to work together in macOS.

I assume you don't have this Black Screen issue when you boot into Windows or Linux.

When I look in my IOReg for the discrete GPU, and specifically the Framebuffer settings the are what I see.

The four Framebuffer connectors are shown.

ATY,AMD,RadeonFramebuffer@0 corresponds with my non-working Display Port connection.
This is what the IOReg shows for this connection:



ATY,AMD,RadeonFramebuffer@1 corresponds with my main display (where the macOS Dock resides).
This is what the IOReg shows for this connection:



ATY,AMD,RadeonFramebuffer@2 corresponds to my second display.
This is what IOReg shows for my second display:



ATY,AMD,RadeonFramebuffer@3 and 4 correspond with the HDMI connectors.
This is what IOReg shows for these two ports, which are both empty.


In each of the screenshots above, the connector type is highlighted. If you look in your IOReg, what does your system show for each port? When only one screen is connected and when two screens are connected, even with a Black Screen, or do you get a black screen on both displays?

I assume you have tried plugging in one of the DisplayPort cables once you are have macOS up and running, to see what happens. What does happen?