I have a system with 2x RX460 cards installed and 2x HD6900 cards on riser boards. All 4 cards show up in the device manager but the HD6900's never accept drivers (automatically or by manually finding them) and only the RX460's show up in applications like Hashcat. In the AMD Radeon settings I only see the 2 RX460's. Attached are screenshots from the device manager and the output from the AMD problem report.
Thanks for your help!