Sapphire RX 580 and Catalina 7mb/8mb VRAM !!

[Gigamaxx]

I tried different SMBIOS (with AMD9500controller.Kext patched)
- 18.3 boot with no fixing
- 19.1 19.2 kernel panic on booting sequence
Does it help you to explain why it's not working ???
Thanks again

it is most likely the vbios on the card. Reading up on these they are really RX570 cards that are sold as 580s. The have 32 compute units compared to the full 36 normally on the 580. They boosted frequencies to try to match the performance of the 580.

One more possibility is to use the device properties data injection and select “load video bios” in clover graphics section.

Then the only other option to make it run in OSX is to flash the bios. Check again on the card to see if it has a dual Bios switch. The switch would be on the opposite end from the 6-8 pin power connector near the display output side of the card. It’s a small switch. If it has dual bios you can more safely flash just one of the vbios to test. If it goes bad you can re install the original.
You need to do it in windows and use the tech power up site bios selections. I would flash with a RX 570 bios from sapphire since the card really is a 570 that way it will likely last longer and no overheat.

If it doesn’t have a dual bios then it is more risky to do. Read all guides before attempting and check out the warnings.

 

[oli.mathieu]

it is most likely the vbios on the card. Reading up on these they are really RX570 cards that are sold as 580s. The have 32 compute units compared to the full 36 normally on the 580. They boosted frequencies to try to match the performance of the 580.

Good to Know, thanks

One more possibility is to use the device properties data injection and select “load video bios” in clover graphics section.

Without any kext patched, I supposed...
Thanks again

 

[Gigamaxx]

Good to Know, thanks

Without any kext patched, I supposed...
Thanks again

Yes no kext patch just add the load vbios.

 

[oli.mathieu]

Yes no kext patch just add the load vbios.

I tried :
load vbios + device-id 67DF000 -> it boots with no fixing
load vbios + device-id DF67000 -> kernel panic during the boot

I'm giving up
Big Thanks to all for the Help

 

[oli.mathieu]

I search setting in the BIOS related to Video.
Does the OPROM can have an impact on that issue?

 

[Gigamaxx]

I search setting in the BIOS related to Video.
Does the OPROM can have an impact on that issue?

yes
You may be able to download a bios file from tech power up and place it in clover ROM folder and get it to load. It’s tricky to do, you have to rename it and specify it in clover.

 

[oli.mathieu]

yes
You may be able to download a bios file from tech power up and place it in clover ROM folder and get it to load.

I did that

It’s tricky to do, you have to rename it and specify it in clover.

A quick search, but I found nothing. Do you have more info about that ?

 

[Gigamaxx]

I did that

A quick search, but I found nothing. Do you have more info about that ?

a long time ago mork vom ork posted it in a Radeon graphics thread here. in thinking 2016-17 or so. I’ll poke around and see if anything pops up.

 

[itwas]

I did that

A quick search, but I found nothing. Do you have more info about that ?

If i were you, I would flash the card with RX 570 VBIOS


Clover Configurator Tips

<key>LoadVBios</key>
<true/>
Loads a video bios from a file, which needs to be stored at the directory EFI/CLOVER/OEM/[model]/ROM or EFI/CLOVER/ROM with the name [vendor]_[device].rom, for instance 1002_68d8.rom. Sometimes it makes sense to load video bios manually, for example when you need a patched version or when the video card does not show it to the system - like mobile Radeon cards. In this case it is enough to set this parameter to Yes without providing any file. Clover will read the video bios from legacy memory at 0xC0000, where it is present most of the times, and enable functionality.
Apparently the video bios written to the card's ROM does not match the one stored at address 0xC0000 - the shadow ROM. In short:

<true/> - Use for mobile Radeon cards without any external file.
Can also be used to supply a legacy video bios to cards, which only contain a UEFI video bios.
<false/> - For all other variants

 

[Gigamaxx]

1002_6fdf.rom or 1002_6FDF.rom
above is what you would rename the tech power up vbios.