iGPU has to be visible AND operational in Windows in order to activate Optimus and use built-in screen with eGPU, but afaik you still can't do it. The reason is proprietary hardware that's implemented by Apple for hard-switching between iGPU and dGPU.
I have a similar rMBP and made native UEFI installation of Win 8 on my external SSD three years ago. Windows was able to detect iGPU, but it'd never load after you actually install drivers for it.
And if you use default bootcamp installation with BIOS emulation, then it'd forever hide both multiplexor and iGPU from Windows and leave dGPU as the only graphics card
I found the way to play games on our RETINA Macbook Pro (mid 2012) with NVIDIA GT 650M!
This trick will work also on the new Macbook Pro 15 with 450, 455 and 460 for sure!
Internal display working (no need for external display)
So the two main limitations with this model of Macbook are the fact that you need an external display, and that you have no sound with an EFI Windows instillation. So I got around those limitations with this little device and three resistors:
It's a HDMI to VGA adapter with audio out. You can see the audio out here:
All you need to do is put 3x 75ohm resistors inside the VGA port to create a fake external display. You can see where the resistors need to go with this image:
So the deal with this is, any program started on the 'external screen' (being powered by the eGPU) will use the eGPU. So what you'll want to do is set the fake display as your main display. Then anything started on that display will be running from the eGPU. Now there is a little limitation here; only games that run in windowed mode will work (which is most). You'll want to start the game on the fake screen in windowed mode and then drag it over to your internal display.
So how do you grab from a display you can't see? Well, I found this free program called Dual Monitor Tools (it's free right here:
Dual Monitor Tools - Home )
and what you can do in this program is set a keyboard shortcut to move the selected window over to the other display. So you click on the game in the task bar, and hit the shortcut you assigned and it'll pop over to the internal screen, but because it was launched on the fake screen, it'll be powered by the eGPU.
Simple as that, there's no performance hit either as you're just dragging the game to the other screen.
A good tip is to have the internal display set as default first, launch the game, go to options and set the game to windowed mode now, then quit and relaunch after you've changed the fake screen as your primary. Otherwise you might not be able to switch it with the shortcut while it's in full screen.
An issue I have:
I don't know if this will apply to others but I simply cannot boot in to Windows with my GT650M activated. My startup process is very odd, so I'll document it incase others have to do this.
To make my Windows even boot, I must have my GT650M disabled in device manger. But when I do this I cannot boot without the eGPU plugged in at all.
So what I have to do is make sure my GT650M is down (boot in safe mode to do this the first time, no need for eGPU attached when doing this).
Then with the eGPU plugged in, start up my laptop and chose the Windows boot option. The only way I know that Windows has successfully booted is the spinning white dots under the Windows logo on bootup will freeze. When my internal display freezes, I know Windows has loaded (this is when the desktop would appear on the external display) but of course we can't see that because it's a fake display.
So once the bootup freezes, I wait until my keyboard backlights come on, then I know the desktop has loaded on the fake display. (Or just wait about 10 seconds after the freeze). Now the next step is to activate the GT650M in device manger so that my internal screen works. Now for this I did the process on a proper external display to learn the key combination to do it blind. For me it as follows:
(Press START - cmd key)
type: device man
ENTER
TAB
Down arrow x8
ENTER
TAB
ENTER
ENTER
After I have done that, the frozen Windows logo will disappear and the screen will flicker for about 5 - 10 seconds before displaying my desktop.
Success! I can now control Windows from my internal display. Opening up the resolution tool will show 2 displays, the internal, and the fake external.
The only thing to remember is when I'm done, I must deactivate the GT650M in device manager again before shutting down. Deactivating it will not shut off the internal display, so it's not a problem to do that and shut down.
So that's it. I hope you don't have to do that process, but for me, that's the only way to do it. it's a slight pain but not too much bother, and it's certainly great not to have to use an external screen!
- full post here -
https://www.techinferno.com/index.p...ps-tb1-akitio-thunder2-win10-lukehero/&page=1