Windows won't boot with egpu connected to thunderbolt

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Level 1

8 points

Windows won't boot with egpu connected to thunderbolt

Hi. I've installed windows with bootcamp. I have an external gpu. Razer coreX. video card is Radeon rx5700xt. When windows is loaded I plug egpu and everything seems works fine. windows recognizes the device. If I boot mac with egpu connected, windows won't load at all. Just black screen. And the only solution is to unplug egpu, restart, and plug it once windows is running. I had the same issue when I ran Ubuntu. It wouldn't load with egpu connected. Is there any security restrictions that prevent thunderbolt egpu from running on boot ? If I start macos it runs with no problems.

Mac mini, macOS 10.15

Posted on Nov 9, 2020 8:01 PM

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Answer 1

Loner T

Level 9

59,536 points

Nov 9, 2020 9:27 PM in response to maxpayne3d

maxpayne3d wrote:

Hi. It's 2018.

What is the Model?

I guess I made it working. I had to unplug any monitors from Mac itself and plug them into egpu. Actually just one for test because I have only one hdmi port on it. But then the question is : is there a way to make it work without plugging unplugg cables all the time.

Not in Windows.

I want to use macos without egpu and windows with egpu but that's a pain to take care of cables every time.

See Use an external graphics processor with your Mac - Apple Support for reference. egpu.io may be the best resource for Windows support.

And it seems like when I boot with egpu internal video card which is Intel uhd isn't enabled. It's not in the system devices.

eGPUs have some advantages, but these can cause new issues.

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Answer 2

Loner T

Level 9

59,536 points

Nov 12, 2020 2:37 PM in response to maxpayne3d

The Monitor detection may work, but the signal handshake may not, with the eGPU in the mix.

There is footnote in the link I posted earlier.

1. If you have a Mac mini (2018) with FileVault turned on, make sure to connect your primary display directly to Mac mini during startup. After you log in and see the macOS Desktop, you can unplug the display from Mac mini and connect it to your eGPU.

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Answer 3

Loner T

Level 9

59,536 points

Nov 12, 2020 3:58 PM in response to maxpayne3d

You do not need to unplug it. It does not harm the Mac. The signal handshake will fail, and you will see a display, which is not there. You may want to designate a different display as your main display.

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Answer 4

maxpayne3d Author

Level 1

8 points

Nov 9, 2020 9:01 PM in response to Loner T

Hi. It's 2018. I guess I made it working. I had to unplug any monitors from Mac itself and plug them into egpu. Actually just one for test because I have only one hdmi port on it. But then the question is : is there a way to make it work without plugging unplugg cables all the time. I want to use macos without egpu and windows with egpu but that's a pain to take care of cables every time.

And it seems like when I boot with egpu internal video card which is Intel uhd isn't enabled. It's not in the system devices.

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Answer 5

maxpayne3d Author

Level 1

8 points

Nov 10, 2020 4:42 PM in response to Loner T

What is the Model?

Sorry. It's Mac mini 2018.

Thank you for pointing to egpu.io. Helpful resource.

I now have another issue. Once running eGPU on windows with one monitor connected to it and another to Mac. eGpu monitor is working well but Mac one is black. Even though windows shows that I have 2 monitors connected. That is using Mac thunderbolt -> monitor . If I plug Mac HDMI -> monitor, sometimes it shows windows logo, sometimes horizontal green lines. I guess that's because internal gpu isn't loaded when egpu plugged in ?

I want to use HDMI switcher. One input will be coming from egpu and another from Mac. So when I want to use windows and egpu I will use switch instead of dealing with cables. But I want to have second monitor always plugged into Mac.

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Answer 6

maxpayne3d Author

Level 1

8 points

Nov 12, 2020 3:25 PM in response to Loner T

FileVault is off. Everything works with MacOs. Regardless with egpu or not. In case of Windows it's a little different. It kind of working and I think I'm okay with the result. I set it up this way. One HDMI from Mac goes to one monitor, one thunderbolt -> HDMI goes to another monitor. One displayport from eGpu goes to one monitor. Another display port goes from first monitor to another one making Daisy chain connection. Everything is okay. Working in windows except that it sees 3 monitors except 2. One of them is HDMI that comes from Mac itself. If I switch one monitor input to that HDMI it has either blue lines or blinking or anything else. Is there a way to disable that one ? Won't it break anything in Mac ? I can live that as long as it's okay to use it that way. Or may be there is a way to disable it at all ? The only drawback is that I can't see login screen in windows because it goes to that 3rd (main) HDMI monitor that doesn't work.

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Answer 7

maxpayne3d Author

Level 1

8 points

Nov 12, 2020 3:40 PM in response to Loner T

Can you please specify what kind of issues ? Can this setup be harmful for Mac hardware ? I mean It's not a problem to unplug that HDMI before running Windows but I don't really want to do that every time.

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Answer 8

maxpayne3d Author

Level 1

8 points

Nov 12, 2020 4:24 PM in response to Loner T

That's the same monitor that is connected to eGpu. I have one monitor connected to Mac HDMI and the exact same monitor connected to egpu. I just switch input on it when booting Windows. But windows recognises it as two different monitors.

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