@franknickzhang Have you had any recent progress? I've successfully been able to boot into Windows 8.1 on a 2015 MBPr 13", utilizing the eGPU. However, I do not get a code 12. Instead the macbook either does not post (ie: non-initialized internal and external screen), I get stuck at the windows boot screen (spinning wheel), or it gets into windows but device manager says that the graphics card is hidden and not connected (code 45). The only way that I've been able to get it to work is by uninstalling the graphics card device and deleting the drivers in device manager, rebooting, it then may be detected as a generic video device, I then reinstall the NVIDIA drivers, shutdown, startup (usually black screen), shutdown, and startup again. This doesn't always work though.