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Only the Blackmagic eGPU has the Thunderbolt controller in the eGPU connected to the DisplayPort outputs of the GPU allowing Thunderbolt displays to be directly controlled by the GPU in the eGPU.

Otherwise the Thunderbolt display must be controlled by the GPU of the computer (unless you connect a Thunderbolt add-in card somehow).

Now if someone could make an eGPU with DisplayPort inputs to the Thunderbolt controller, then that would take away the only real advantage of the Blackmagic eGPU. Low noise isn't a great advantage, and they don't even mention that with the new Blackmagic eGPU Pro with Vega graphics.
 
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