AppleInsider testing has shown significant improvement in eGPU implementation in Apple's new macOS 10.13.4 beta, boasting a dynamic clamshell mode working as expected regardless of monitor configuration, and a new menu on the desktop allowing users to disconnect from a connected enclosure without necessitating a logout.
The new menu item at the right hand side of the menubar is simple -- it only has two options. Either there is no "removable GPU" or there is, and it can be ejected.
Under the new beta, an external GPU can be connected while the machine is running, and it will not pop up a notification to logout to enable the GPU. Rather, it connects automatically, and shifts to the previous configuration.
Before High Sierra 10.13.4, clamshell mode was partially implemented. If the displays were mirrored to begin with, if you shut the lid on a MacBook Pro it would turn off that display. However, if you had two workplaces, the workspace on the MacBook Pro's screen would remain active, even with the lid shut.
With the new release, Clamshell mode implements properly on lid-shut, even with a workspace spanning the MacBook Pro's internal display in conjunction with external displays.
AppleInsider has tested the improvements and new functionality on the Sonnet eGFX Breakaway Puck with RX 560, the Sonnet and AMD RX 580 developer's kit that Apple briefly sold during the initial beta releases of High Sierra, and the Mantiz MZ-02 with a Vega 56 PCI-E card.
Apple's support for external Thunderbolt 3 enclosures containing a PCI-E GPU began following the 2017 WWDC. The feature, while present in all High Sierra builds, is still considered a beta. Apple has announced that support for external GPUs will be fully supported in the spring.