iMac 2017 with OCLP macOS Sequoia - RX580 not in use?

[rxtc]

I have installed macOS Sequoia 15.5 on a 27“ iMac (iMac18,3 from 2017) with 4.2 GHz i7 ”Kaby Lake" and Radeon Pro 580 8 GB with OCLP 2.4.0. The iMac18.3 was selected as the preset in OCLP. The Radeon is displayed in “About this Mac”.

Everything is running smoothly and without any software problems. However, there is one thing that bothers me immensely: as soon as anything graphics-intensive is called up, the fans slowly but continuously turn up to a considerable volume. This starts with the Sequoia screensavers and becomes really blatant when watching several videos at the same time.

I have therefore installed Macs Fan Control to see what happens. The cause is obviously the “GPU Intel Graphics KBL”, whose sensors then show almost 100°C under load, while the actual graphics card “GPU Radeon Pro 580” remains at around the case temperature of 40-45°C. I conclude from this that the Radeon 580 is recognized under Sequoia, but is not used at all. Even in Videoproc Converter, only the “Intel HD Graphics KBL” is displayed in the graphics test.

Is this behavior normal or can I force the use of the RX580 somehow, e.g. with a special driver or a setting that I may have overlooked? I'm annoyed by the massive fan speed, but I don't think it makes sense to reduce it using Macs Fan Control.

Does anyone have any suggestions?

 

[Dimvol]

It uses the integrated video accelerator only for calculations, it is not used for picture output. This is how it should be, the discrete video accelerator always works. H.264 video decoding is done by the integrated video accelerator and there is hardly a hardware H.265 decoder. You give too little information about what you are playing.
In addition, as for the decoders in Sequoia, they do not work there at all.
The videoproc should have indicated to you that there are no decoders.
This is a known problem with OCLP and Sequoia. There will be no solution. You will have to go back to Sonoma with OCLP or Ventura.

 

[Dimvol]

I don't have an iMac 2017 anymore, I had it half a year ago. But mine had a Pro 560 and it wasn't enough for me. If mine had a RX580, I wouldn't have parted with it.
To make it clear what we're talking about.
Old versions of VideoProc show only an integrated video accelerator, new ones show a discrete one.
HD630 can't work in Sequoia. But even if it did, there won't be any H.265 decoders.

You can force the system to use the decoders of the discrete video accelerator. To do this, there is a set of commands that need to be run in Terminal (for example, defaults write com.apple.AppleGVA gvaForceAMDHEVCDecode -boolean yes - will enable HEVC decoders).
But all these properties have long been removed from MacOS.

They can be returned manually.
But it will be better if you return to using Sonoma or Ventura.