atlr

I do not see a Thunderbolt header in the documentation of the ASUS Pro WS C621-64L SAGE/10G . I noticed some re-sellers list Thunderbolt support for this motherboard but ASUS.com does not. I have tried using Thunderbolt add-in cards on motherboards that were not made to support them and it's not a smooth experience. Productivity will suffer if you choose this kind of setup. egpu.io and avid messageboards are good sources of info on thunderbolt and audio workstation topics. (I am not affiliated with either one).