2016 TB MBP + AMD RX 580 eGPU, no LG Ultrafine 5K joy
So.. following @itsage's guide through fits and starts, I have Error 12 cleared up in Win10 on my 15" 2016 touchbar MBP. But.. I'm having no luck at all getting the LG Ultrafine 5K connected (so, hey, as a result, no display is actually using the eGPU right now). After Windows finishes booting, when I connect the LG, windows gives me an "unknown USB device" error. I can see its camera in device manager and I am getting audio, but it fails to actually use it as a monitor. If I boot with the LG connected, around halfway through the boot cycle the MBP shuts back down, and the eGPU needs a power cycle to want to connect on next boot. Any advice on where to go from here? eGPU is connected to back-right Thunderbolt port, and using back-left for the LG. (Also tried front-right for the LG.)
Did you disable the PCIe Controller (x16) - 1901 [to Radeon dGPU] in Device Manager and confirm the internal display is attached to the Intel iGPU? I would say to test whether the Intel iGPU can power the LG 5K UltraFine in Windows before connecting the eGPU.
Here's the device manager state. 1901 is disabled. With eGPU connected, LG still gives the same error.
OS X behavior is that the Intel will drive the internal display OR the LG, but never both at the same time. (I have no external keyboard, so I'm always running laptop open).
I had the same experience with my 2016 15 inch. I found it was DDU that was causing the issue, after removing drivers my 5k would go blank and even installing new AMD drivers didn’t fix it.
Try a vanilla windows instal and then simpler instal methods until it works. I had a Nvidia card working with mine and it was nearly plug and play I think (since sold it).
2017 13" MacBook Pro Touch Bar
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My current "simpler install" is plugging the eGPU into an HDTV via HDMI I was interested to find that I had to tell Windows to allocate the eGPU to the app.. even though the app was wholly contained within the TV, the default was wanting to use the Intel to drive it and have the eGPU as a pass-through. This might be a clue that somehow the eGPU isn't being treated as a first-class citizen and thus won't allocate itself wholly to a display. Just a theory, though, and I'm not sure how I would go about testing it.