MP 1,1-5,1 Help Needed With MP 5,1, No External 2nd Display Monitor Found?

[Phazemonster]

Hi All,
I seeking help and I am new here, I was able to edit video out to my 2nd monitor with a RX580 Radeon Pulse just fine in Final Cut X running High Sierra until I upgrade to OpenCore and Mohave. I couldn't adjust the settings under the preferences and booting up I could see OC, on my 2nd monitor on the boot screen with OC at startup. I tried a pvram reset and nothing changed, now my monitor says no cable found, and I even went out and got a new HDMI cable. I also put in a metal capable flashed Apple compatible card and restarted in Windows on a bootable Windows drive and the 2nd monitor still is now seen? I uninstalled OC, and currently downgrading to High Sierra from Mohave of Which I was running BootRom 144.000 from Mohave prior to installing OC, And suggestions?

Thank You

2009 MP, 4,1, converted to 5,1
2 x 3.33 GHz 6-Core Intel Xeons
Radeon RX580, and a NVIDIA GeForce GT 640 1 GB, secondary card, flashed Apple boot screen
48 gb of memory
Mohave 10.14.6

 

[tsialex]

You are using both cards at the same time? If so, this only kinda works for dissimilar cards and just up to High Sierra.

Use only one GPU, connect both displays to the same card and remove the other GPU.

 

[Phazemonster]

You are using both cards at the same time? If so, this only kinda works for dissimilar cards and just up to High Sierra.

Use only one GPU, connect both displays to the same card and remove the other GPU.

Hi
I tried both separately already, this started acting up after OpenCore installation and I uninstalled OC already maybe downgrade to HS,

Thank you

 

[tsialex]

Hi
I tried both separately already, this started acting up after OpenCore installation and I uninstalled OC already maybe downgrade to HS,

Thank you

Using dissimilar GPUs after High Sierra is not supported (it was never really supported mixing NVIDIA and AMD GPUs, but more or less worked good enough up to High Sierra), so use only one GPU.

All sort of weird errors happen when you try this with Mojave and newer macOS releases, from Finder window problems to really weird crashes.

Do a clean install of Mojave with one GPU, get your Mac Pro working reliably again, then you later enable VideoToolbox hardware assistance for video grading/coloring/compressing/decompressing (what is commonly called AMD hardware acceleration) for your RX 580 with OpenCore.

 

[Phazemonster]

This initially started with the RX580 after the OC installation in Mohave and I had no signal to FCP X, I booted up and the OC boot screen appeared on the 2nd display and the jumped to the main monitor screen and I tried to adjust the settings in the Display preferences then it disappeared altogether, no more 2nd monitor
Thank you for being here

 

[Phazemonster]

Hey I got it resolved! Took out the GPUs and reseated the RX 580 and adjusted the screen display preferences and all Is fantastic now
Thank you very much for your help today and being here!