I had a search and couldn't see the issue mentioned so a heads up to anyone else with a C1 and 6800xt. Radeon driver 21.4.1 and 21.5.1 broke freesync so you get stuttering in windows menus, games etc. I tried all the usual stuff but no luck, clean install, yes the cable is fine, no suspect windows update etc. Rolling back to 21.3.2 fixed the issues.
Oh and when is AMD going to support VRR properly?