The Black Magic Design RX580 External GPU is a relatively inexpensive way to accelerate graphics processing on USB-C Macs. Uses include rendering time-lapse video, video editing, and faster gaming. It’s powerful and quiet, but consumes a lot (350W) of electrical power. It also acts as a hub with 4 USB 3 jacks, an HDMI 2 port, and a second USB-C port.