Hello
@imcalledandy,
Welcome to the forum! Was the Thunderbolt firmware flashed when you were running Catalina, or did you flash the firmware after upgrading to Big Sur? Because the eGPUs were working in Catalina, I assume firmware was flashed back then?
- What are the makes/models of the two eGPUs?
- Which one works in Big Sur and which one does not?
- What are the makes/models of the GPUs inside each eGPU chassis?
Please clarify if you flashed the firmware after upgrading to Big Sur or it was flashed earlier when you were running Catalina?
This just means that the Thunderbolt SSDT you're using is not properly set up. Please post the following files:
- IORegistryExplorer --> File --> Save As...
- The Thunderbolt SSDT you're currently using
This is typically resolved by fixing the Thunderbolt SSDT (see above).
Please clarify whether (a) both graphics cards in both eGPUs do not show up or (b) one of the graphics cards in one of the eGPUs shows up?
- Is this in Catalina?
- Your first sentence states that both eGPUs were working in Catalina...
As you can see, it's vitally important to provide details clearly. I always encourage everyone to use bullet lists instead of lengthy paragraphs.