Help. I am hitting a brick wall.
I'll make a quick summary.
As I have said in earlier posts, I got myself a Saphhire Pulse RX 580. Not knowingly I got the wrong version and got the 2048SP version which is a Chinese SKU and is not recognized by macOS. I eventually got it to work by editing the VBIOS and changing the dev ID as described
here. So that was nice except I was not getting boot screen. So I injected EnableGOP to the MAC's ROM. That didn't help. So I went on a quest to find a new VBIOS for the GPU in the hope I could find one that would enable boot screen. No luck there either. I've been lucky not to brick the card so far. Anyhow then I realized I could ask directly Sapphire to send me the actual factory VBIOS of that card. That was the right move as they sent me the factory VBIOS and I was finally enable to have boot screen. But the excitement was short lived. I soon realized that macOS was not detecting the card correctly and I was only getting a simple display output with no acceleration. Image was sluggish, same as if you boot in Safe Mode. See screenshot below:
As you can see no card detected and no Kext loaded.
So I thought I could go back to the initial trick which consisted of minimally editing the VBIOS so that it showed as an RX 570 or even RX 580. It worked.... except I lost boot screen again. This seems to imply that any editing of the VBIOS, as minimal as that is, invalidates the card's UEFI GOP and boot screen is therefore unavailable.
I have been digging right and left to make this card work 100% but so far I have failed. I have also asked Saphhire to send me a factory VBIOS for an RX 570 but so far they have refused to do so.
So this begs the question. Is this possible to have this card modded so that macOS recognizes it as an RX570 or RX580 and at the same time allow boot screen?
Any help would be appreciated as I am now out of ideas.
And many thanks and appreciation go to
@h9826790 who has been helping me in the background.
In case anyone asks, attached is the factory BIOS sent to me by Sapphire. I also
uploaded it directly from GPU-Z to techpowerup but it seems one value was changed by GPU-Z during the dump/upload. In fact if I download back the BIOS file from techpowerup, amdvbflash refuses to flash it to the GPU with an "Invalid PC BIOS image" 0FL01 error. I think that is due to the fact that there is an invalid checksum due to the value change. So better use the attached file.