Thunderbolt ports can't be added to existing PCs via an expansion card; Intel says the only way to have it is to buy a system or logic board that incorporates the new Thunderbolt controller chip. That's because the Thunderbolt chip needs direct access to both the system's video and PCI Express architecture.
Does this imply that 3D work performed by the AMD GPU has to travel back through the PCIe bus in order to be displayed through a Thunderbolt connector?