As of 10.12.1 Beta 1, RX 470/480 work great inside a tower Mac Pro and eGPU for Mac laptops with Thunderbolt.
https://forums.macrumors.com/thread...-akitio-thunder2.1988609/page-3#post-23511733
eGPU w/ MacBook Air 11"
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3-way Crossfire in Mac Pro 5,1
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I've always wondered why they had to put the eGPU inside enclosures. That eGPU you have looks sick!