Black screen at login after downgrading from RX 580 to GTX 770

It's a Ryzen 9 3900X AsRock ITX/TB3 - 10.14.6 Mojave.

I've tried iMac14,2 instead of iMacPro1,1 and DVI/HDMI and screen is still black.

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Are there any boot args I could try besides shikigva=40?

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The RX 580 suddenly stopped working and had a GTX card I used that works in a MacPro also on Mojave, right before. Also works in Windows.

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Thank you