[Solved] How to: internal -> dGPU, external -> eGPU under windows
I ran into problems with my eGPU setup. My goal is to run my internal screen with the dGPU of my iMac and the external monitor with the eGPU. The eGPU is connected and works fine, that said it runs the external monitor just fine. But the internal monitor seems to be running with the eGPU as well. And that is causing some problems, I think. Because the task manager says eGPU's usage is 100%, fans begin spinning, the eGPU gets hot, but it is not possible to watch a 4k youtube video without stuttering on the internal screen then.
The problematic thing is, I can only get my internal screen going if I made windows recognise the iGPU somehow (at least that is what the information I gathered in many threads are telling me). This, I have done either by
a) using the efi method -> this results in iGPU and eGPU recognised correctly in the device manager but dGPU not (error 43)
b) booting into windows with only using the DSDT override, then disabling the dGPU in the device manager and rebooting again -> internal screen is working without anything else but the device manager doesn't show the iGPU at all, the dGPU was disabled by me and the eGPU recognised correctly.
So I do not know what to do at the moment. Should I either try to get all 3 GPUs recognised correctly by the device manager, or trying to tweak stuff so the eGPU can run the internal and external screen at the same time?
I thought it is a simple thing to use the dGPU for the internal and the eGPU for external monitor, but I am stuck. Can anybody help me out? Give me a hint or some useful information regarding that topic?
Sooo... it has been a while, but...
I finally managed that my iMac recognizes both dGPU and eGPU without the iGPU showing up in the device manager (that caused the dGPU error 43) -> can not run all three detected correctly at the same time.
I booted into windows with the DSDT override and the apple-set-os.efi -> same behaviour as described in top post under a) ->
Then I uninstalled the eGPU in the device manager. Because I booted with apple-set-os.efi, I have my internal screen working with the iGPU and I am able to restart the system ->
Then I restarted and I made sure to boot into windows with the DSDT override BUT without the apple-set-os.efi this time (which was used to get the internal screen working). For a specific reason I read in this forum (but forgot who said it, no reference here, sry), the previous uninstallation of the eGPU causes the system to boot with the dGPU using the internal screen. Then after booting into windows completely I could see the eGPU correctly recognized together with the dGPU. The internal screen was working. 'Windows + P' and 'extend' for the external screen and here we are. Both screens working with both the dGPU and eGPU correctly recognized in the device manager without the iGPU. Now, with the help of the windows graphics settings, I was able to specify which application should use the dGPU.
Now I am searching for a method to tell windows that the dGPU not the eGPU should be the default graphics option. It would be much easier this way than the other way around. All applications should use the dGPU and be displayed on the internal screen. Only my game application displayed on the external screen using the eGPU. That is the goal!
UPDATE: The windows graphics settings do nothing for me. It is not reliable at all. The only clever way to get the applications managed is to 'Windows + P' and PC screen only -> Then launch all the applications u want to use on the dGPU and then switch to 'Windows + P' and 'extend' (external screen is set to main screen in the display settings). Then u can launch the game u wanna play. Seems a reliable workaround to me. I was not able to force applications into using the dGPU with the graphics settings. But windows seems to manage it in regard to the set main display that is active at the moment u launch an application. Got reliable and reproducible results with this method (monitored with task manager performance activity and the AMD XConnect programm).
Update: The recent windows update September 10, 2019—KB4515384 (OS Build 18362.356) destroys my setup right now. The described method does not work anymore. I had to use a restore point to be able to use my system as usual. I guess I will stay on the previous build for a long time now.