The recent rise of Thunderbolt 3 ports and external graphics enclosures to go with them has cracked a door to an intoxicating vision of the future: a world where gamers carry thin-and-light notebooks without power-hungry discrete graphics chips inside to class or work. Once they're back at their desks, those same folks plug in a single cable from an external graphics enclosure and get all of the pixel-pushing power of a desktop graphics card. That's the dream, anyway. The reality of Thunderbolt 3 and external graphics is a lot more complex.