Help: Graphic Glitches Sapphire RX 580 GA-Z270

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Hi everyone,

 

I looking for some help with graphic glitches on my current set up.

 

Gigabyte GA-Z270-UD5, Sapphire RX 580 Nitro+, Intel i7, 7700k 4.2ghz

 

I previously had a stable system with the same Hardware and a Geforce GTX 1060 graphics card. It powered two Dell displays (P2715Q) via displayport. It ran very well on High Sierra for several years, and would stay up for weeks on end without issue (one Dell monitors graphics might shake occasionally - but as that was the only issue I observed - I lived with it).

 

I got bored of Apple/Nvidia and the drivers issues which kept me on High Sierra and bought a Sapphire RX580 Nitro+. I directly replaced the Geforce GTX1060. I uninstalled Nvidia drivers, and updated kexts with latest Whatevergreen, Lilu etc. This resulted in glitchy graphics on High Sierra. The glitches can appear anywhere on either screen and manifest themselves as oblongs or triangles which stretch wholly or partially across the whole of the screen (not just an active window). They appear to flash with what should be on the screen and white/ grey block colour. They are more likely to appear if I play a youtube video etc. The video and sound of the video is otherwise perfect.

 

I have looked into Artifacting - and the glitches don't look to me like the type of thing people describe, and the videos online of artifacts in games etc. I have attached a picture of the glitch in Catalina. You can see a triangle / oblong emerging from the bottom left of safari, which is playing a music video, stretch all they way up and to the right through safari and ending at the top of the screen with the desktop behind. In real life this is flashing white / grey at a rapid pace.

 

On booting, I would say I successfully get to the log in screen about 50% of the time. The other 50% the apple logo and white bar stop at 100% and the system proceeds no further and requires a hard reset. At the login screen, sometimes the graphic glitches appear, sometimes not. On entering my password sometimes I get to the desktop, sometimes a freeze occurs at this time, and a hard reset is required. Once on the desktop the above mentioned graphic glitches appear. They system will eventually freeze and a hard rest will be required. However the system can stay up, running video with the glitches for a good 20 minutes before freezing.

 

I went for a fresh install of High Sierra, (with no file migration, or any applications installed etc) and this makes no difference to the observed graphic glitch behaviour.

 

I tried fresh installations of both Mojave and Catalina, and successfully achieved both. But the graphic glitch issue remains, and is identical in all 3 operating systems. I am currently attempting to solve the problem in Catalina.

 

I have always run with an 18,3 system definition - and High Sierra and the GTX 1060 were quite happy with that. I have also tried, with the RX 580, a pro 1,1 definition with no change in behaviour. I have tried running with the iGPU enabled and disabled in bios with no change in behaviour. I have relied on Whatevergreen, but have also tried manually running the HD 630 iGPU as headless, by changing the settings in Clover configurator. Hackintool indicates this is successful with dummy ports showing. No difference was observed. (I would generally describe the system as quite robust when it comes to the bios. I have followed the various guides for bios settings, but generally it is rare that a change in any of the bios settings puts the system off booting or running).

 

The new card itself is plugged into a Corsair RM650x. 8 pin connector in the psu to an 8 pin and 6 pin splitter which attaches respectively to an 8 pin and 6 pin socket on the card. I don't get any sense that the card is under powered. The card works well in Windows 10 on the same set-up, and breezes through any stress test programs.

 

EFI folder attached.

 

As you can appreciate this is driving me nutts. Just can't suss it.

 

Any and all help much appreciated.

EFI.zip