I could have written this same post with the topic:
Problem, but is it Mojave or the Radeon RX VEGA FRONTIER EDITION, both newly installed?
Of course my problem is sufficiently similar that i'm not going to start a new thread.
It seems it was solved by replacing the GPU.......... I'm a little troubled by this due to the cost (ebay purchase) of the VEGA FE but if it fixed everything it may be my only option.
It feels like a very similar problem but it's weird.
PCIe register shows the Radeon RX Vega FE 16GB. So..
(1) it has correctly identified the card [board_id] *BUT*
(2) System Info is lying to me - it says the GPU is connected at x16. This is impossible because it's in a x8 slot in my NETSTOR PCIe expansion box - a TRUE negotiated link speed would say x4 or x8.
This means the device description is hard-coded NOT calculated / 'evaluated'
Anyone able to diagnose the point in the system POST / boot process where the failure occurs?
IIRC.. the system queries (or 'evals') SATA, then xHCI, then PCIe but the behaviour of the display performs very much in line with the "unaccelerated" characterisation made by
@tsialex in an earlier post.
Is this possible? The GT120 has the 'fallback' MAC EFI drivers to boot with 'unacceleraed' graphics? The VEGA FE doesn't have the fallback drivers does it?
Any thoughts/comments very welcome?
(In the mean time I will troubleshoot with a Radeon RX480 I have in storage)