Can't USB boot windows with MSI motherboard

[Keb180]

Hello everyone,
some days ago I managed to build a PC with
- Intel i7-6700K 4*4 GHz
- 16 GB RAM, 2133 MHz
- MSI Nvidia GTX950
- MSI Z170A PC Mate motherboard
Today I tried to plug in my USB-HDD with Windows 7 - bluescreen. When I choose the repair option on a installation disc the HDD won't show up in the list, only the SATA one which I don't need at the moment. It's already difficult to get to the repair tool because mouse and keyboard won't work if you don't switch off XHCI Hand-off and turn on Windows 7 Installation in Windows OS Configuration. Turning on USB-Legacy doesn't change anything.
Everything was working on other PCs - for example on the Dell Optiplex 755 which I used before.
I hope someone can help, it's a pretty uncommon situation

 

[ArtPog]

Your description of the problem you're experiencing is quite difficult to understand and it would help if you would clarify the problem in understandable terms.

1. You're apparently attempting to install a Win 7 OS onto a newly-built PC. You say you "tried to plug in my USB-HDD with Windows 7" presumably to install the OS. Does this external USB HDD contain the MS Win 7 installation setup files? Or are you indicating this drive contains a Win 7 OS?

2. When you mention "Everything was working on other PCs..." including an OEM PC, what does all that have to do with your problem? Are you indicating you're using components in this new build cannibalized from "other PCs"? If so, I trust one of them isn't your MSI motherboard!

3. In your list of components of the "new" PC there's no mention of a HDD or SSD. Is there one? Or is this the "USB-HDD with Windows 7" you've indicated?

 

[Keb180]

Your description of the problem you're experiencing is quite difficult to understand and it would help if you would clarify the problem in understandable terms.

1. You're apparently attempting to install a Win 7 OS onto a newly-built PC. You say you "tried to plug in my USB-HDD with Windows 7" presumably to install the OS. Does this external USB HDD contain the MS Win 7 installation setup files? Or are you indicating this drive contains a Win 7 OS?

2. When you mention "Everything was working on other PCs..." including an OEM PC, what does all that have to do with your problem? Are you indicating you're using components in this new build cannibalized from "other PCs"? If so, I trust one of them isn't your MSI motherboard!

3. In your list of components of the "new" PC there's no mention of a HDD or SSD. Is there one? Or is this the "USB-HDD with Windows 7" you've indicated?

I have Windows already installed on my local HDD that is built in the new one. I also have a USB-HDD on which I installed Windows 7 Professional (not the setup, real OS) too so that I can take it with me. The problem is that I can`t boot from the USB-HDD, because it just shows a bluescreen after it shows the Windows flag.
Booting from the USB worked on other PCs, and no parts of them were used to build the new one.

 

[ArtPog]

Are you indicating that this USB external HDD contains a "universal" Win 7 Professional OS that can be installed on various PCs?

Assuming that this OS could be installed on your new MSI-based PC, how would it be activated? You have a valid Product key for this OS?

 

[Keb180]

Are you indicating that this USB external HDD contains a "universal" Win 7 Professional OS that can be installed on various PCs?

Assuming that this OS could be installed on your new MSI-based PC, how would it be activated? You have a valid Product key for this OS?

I installed "the normal" Win7 Pro with a downloaded ISO on the external USB HDD, when looking at right-click Computer-> Properties you could see "Microsoft" as manufacturer. I have bought a seperate winkey for the USB-HDD. The OS was fully installed with WinToUSB, just like on a internal HDD (windows doesnt allow you to install on usb hard drives)

For the new, MSI PC I used another key (which was used on the old Dell), and I installed Windows with a Dell OEM CD, it works fine so I dont bother about the new installation.