@Leesureone @CaseySJ
Maybe I wasn't lucky with the Asus Z590i Gaming Wifi. But I wasn't able to get Thunderbolt working properly.
I was once able to Hotplug my TB-SSD. And then macOS crashed. And since then I couldn't get it working again.
And I could never get my Razer Core X with the W5500 running. So macOS was only booting in the mode where the CPU is generating the graphics.
Even in Windows it doesn't get detected.
And I tried everything. Several BIOS versions, Enable/Disable Native OS Security, Enable/Disable Force GPIO Power, Enable/Disable the TB-SSDTS, different TB-SSDTs...nothing worked.
Even in Windows with the Windows Boot Manager I have TB-issues now. My TB-SSD is not detected anymore.
So I will switch back to my Z590i Vision D tomorrow. At least Thunderbolt was working when the devices where plugged in before turning on the PC. Even daisy chaining TB devices and attaching the eGPU behind my OWC TB4-Dock worked. The only caveat with the Vision D is, that you don't have Hotplug. But at least TB is working with all my TB devices (TB SSD, OWC TB4 Dock and Razer Core X eGPU Case).
Best,
Chris