MP 1,1-5,1 RX 580 showing nothing on Mojave, HELP!

[Apple Fan 2008]

I have an RX 580 installed in my 5,1 2010 Mac Pro. It used to work fine under Mojave but after a while, it stopped working. When using open core, I can see that it’s loading into the OS, and then just shows a black screen instead of anything for the login page.

 

[Dayo]

Seems you are saying that the GPU shows the OpenCore display, you select the option to boot Mojave, you see the progress bar but when the login page should display, you get a blank black screen instead. Is that indeed the case?

 

[Apple Fan 2008]

Seems you are saying that the GPU shows the OpenCore display, you select the option to boot Mojave, you see the progress bar but when the login page should display, you get a blank black screen instead. Is that indeed the case?

Yup

 

[Dayo]

Means something installed in Mac OS is hijacking the video output.

Some video conferencing tools can have this effect. Try to recollect whether you installed any such, or plugins/modules for previously installed ones, consider unistalling such and checking their support pages.

If you can't recollect what you may have installed/activated, you may need to restore a Mac OS backup saved before you started seeing this issue.

 

[Apple Fan 2008]

Means something installed in Mac OS is hijacking the video output.

Some video conferencing tools can have this effect. Try to recollect whether you installed any such, or plugins/modules for previously installed ones, consider unistalling such and checking their support pages.

If you can't recollect what you may have installed/activated, you may need to restore a Mac OS backup saved before you started seeing this issue.

Hmmm… I do have Steam installed..

 

[Apple Fan 2008]

Hmmm… I do have Steam installed..

Except the stock card works (under opencore of course

 

[Dayo]

You can always try another GPU, if available, to see if you get the same result

EDIT
You were thinking the same.
Well, something must have changed either way. So you need to figure out what that was and reverse it.

 

[Dayo]

Just a thought ... you could try booting Mac OS in Safe Mode with the problem GPU attached.

If you can see the login screen etc with this, then it would suggest some third party kext, or similar, being loaded by Mac OS is indeed responsible as such would be disabled when booting in this mode.

Misc OpenCore Hotkeys: https://forums.macrumors.com/posts/31216031

Separately, since Mojave is natively supported on your unit, you could disconnect the disk with OpenCore and try to boot into Mojave directly.

EDIT
You may need to reset NVRAM to boot natively, so make sure you disconnect disks with any non Mac OS installations as well.

 

[Macschrauber]

Side question: what is the index key? Do computing since the 80s but never came across an index key in my area.

 

[Dayo]

Side question: what is the index key?

Could be a typo and should have been Insert.

 

[Dayo]

What is the index key?

Could be a typo and should have been Insert.

Index apparently stands for the alphanumeric value of the boot entry.
So, for the item booted by Key 1 and for that booted by Key D, Index is 1 and D respectively.