Doesn't anyone have any ideas?
It is absolutely not software problem. Try to swap your cards .And upload here pictures from device manager and GPU-Z.
Your system information is not full (or correct) INFORMATION REQUIRED WHEN POSTING A QUESTION
You may also update (or rewrite) your BIOS or reset it. Solve a problem with PCI-e ports first.Raid array may wait.
Can you see both cards in BIOS?
Don't think the bios shows any pcie devices. I can see both cards in the driver and device manager.
I am using the latest drivers.
I managed to solve this problem.
First I removed all drivers, deleted anything AMD from all the drives. Then removed the second card from the motherboard.
Restarted in safe mode and ran DDU, then ran the AMD uninstall tool.
Restarted and installed the latest drivers.
Shut down and installed the second card.
Restarted and both cards were in the driver etc. I could then turn on crossfire. However the performance was quite poor.
After another restart it was working fine.