After spending way too much time window shopping and comparing, Tiamat has been updated to what will probably be its end state for hardware (except drive replacements.)
* Replaced the Ryzen 5 3600 with a Ryzen 5 5600X
* Finally pulled the trigger and updated the GTX 980 TI FTW's to an XFX Merc RX 6800 XT
Thermals are not terrible so far, even in a case that isn't the best for airflow. I've only run it for an hour or so with a AAA game thus far, so we'll see over time if that changes.
RX 6800 XT is installed and ready to go. It BARELY fits, and is actully slightly touching the rad.
Fired up and working away.