Right and 640k ought to be enough for anybody. remember that little gem?

If cost is not an issue, why not just get him any thunderbolt-equipped MacBook and an eGPU box with a GTX970(unofficial) or Radeon RX580 (official support) in it? all I do is reboot into windows and game in bootcamp, then reboot into MacOS for everything else. it's super easy to do and solves all my problems.