Open Core fresh installation to boot with iGPU HD 4600 and RX 580

[endryha]

Indeed iMacPro1,1 is a good model ID to use when you disable the IGPU in BIOS.
I use that config on my 3rd Gen i7-3770K with RX580 and HEVC & H.264 playback is silky smooth with little or no load on the CPU. The decode is offloaded to the RX580.
In the VideoPro App, it can fully transcodes H.264 to HEVC completely via the RX580 with very little load on the CPU.

Thank you for sharing your experience, could you please advise, are there any other changes required to the OpenCore config beyond SMBIOS change?

I mean, if I take my existing configuration and adjust it with new SMBIOS iMacPro1,1 and new serials, would it work out of the box, or, there some additional configuration?

 

[endryha]

Not sure how to verify that the Vbios is the Sapphire OEM version. Doing some googling would likely yield some answers there.

Apparently, the vbios was original from the very beginning, I flashed OEM vbios and still getting the same issue...

 

[macnb]

Thank you for sharing your experience, could you please advise, are there any other changes required to the OpenCore config beyond SMBIOS change?

I mean, if I take my existing configuration and adjust it with new SMBIOS iMacPro1,1 and new serials, would it work out of the box, or, there some additional configuration?

No other changes required to the config. Just change the Generic Section's model id to iMacPro1,1 and appropriate serials for that model. But, disable the IGPU in BIOS.