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MP 1,1-5,1 SOLVED cMP3,1: Black screen on El Cap after failed High Sierra install

pullman

macrumors 6502a
Original poster
Feb 11, 2008
561
77
'(,,,,)°l°
I accidentally posted the below in the MacOS forum and only realised this now. I hope it's OK that I post it here instead.

I installed @dosdude1's High Sierra on my cMP3,1 (specs below). Because my main GPU is a non-EFI Nvidia Quadro I had to use my somewhat unstable AMD 5870 Mac Edition which keeps cutting video randomly when it heats up. This caused difficulties during the installation as the screen would regularly go black and I wouldn't know how far the installation had gone.

Eventually I managed to install High Sierra when the 5870 played along nicely this morning. But I still didn't get video in High Sierra when I switched to the Quadro card. I had not installed the AMD patch because I had read that it could mess with Nvidia cards. This lack of video surprised me because the Quadro card always worked in El Cap even without the web drivers.

Because the 5870 began acting up again after a while I simply had to apply the AMD patch to be able to see the screen, so I did.

Then I ran the amdgpupatchuninst script (twice) to hopefully remove the AMD patch and get video on the Quadro card, but that was unsuccessful because the Patch Updater tool still said that the patch was in place.

I was not able to install the Nvidia web drivers for High Sierra because I could not find a valid driver for the particular version of High Sierra that Dosdude1's patcher had downloaded (17G66).

Eventually I caved in and formated the High Sierra volume.

But the lack of video on my original El Capitan volume persists. I have uninstalled the Nvidia driver and reinstalled the same driver to no avail. I have also tried the default system driver but the black screen is still there. I have checked cables and tried all four connectors on the Quadro card but nothing gives me video.

Has anyone encountered this after removing a patched High Sierra install?

Thanks heaps in advance.

Philip
 

pullman

macrumors 6502a
Original poster
Feb 11, 2008
561
77
'(,,,,)°l°
It seems the BCM94360CD wifi+bt card I installed to be able to get wifi under High Sierra interfered somehow with video. Swapping it out for the Mac Pro 3,1 original cards made video come back. Interestingly video remained after I again installed the 94360 card.
 
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