Onboard graphics output not working with dedicated graphics card installed

[JoeR131]

Working from home on a borrowed office computer that I need to add some additional monitors to. Was running three screens (two off integral displayport outputs and one off the VGA) with no issues but need to get a couple more on to replicate workplace setup. I bought a Palit GeForce GTX1050Ti card and installed, computer starts up fine and I can use the outputs of the dedicated card with no problems. If I try and connect my screens to the integrated outputs though with the card installed, the monitor will connect for a moment, I will get a signal and then within a few seconds the screens will go off and I'll revert back to the login page (with only the one monitor on and others dark). If i log in - same thing will then happen. According to the maintenance and service guide http://h10032.www1.hp.com/ctg/Manual/c04331008.pdf I think I should be able to use all outputs so not sure whats going wrong!

"When a graphics card is installed in one of the system board slots, the video connectors on the graphics card and
the integrated graphics on the system board may be used at the same time. However, for such a configuration, only
the display connected to the discrete graphics card will display POST messages."

[Prométhée]

hi

The system board graphics can be disabled by changing settings in Computer Setup

did you find something about it

Table 8-5 Computer Setup—Advanced (for advanced users) (continued)

Integrated Video (enable/disable). Use this option to disable the integrated video controller
when another video controller is present in the system. Default is enabled

integrated Graphics (Auto/Disable/Force) Use this option to manage integrated (UMA)
graphics memory allocation. The value you choose is allocated permanently to graphics and is
unavailable to the operating system. For example, if you set this value to 512M on a system
with 2 GB of RAM, the system always allocates 512 MB for graphics and the other 1.5 GB for
use by the BIOS and operating system. Default is Auto which sets memory allocation to 512
MB.

[JoeR131]

Hi there. The issue is that I don't want the system board graphics to be disabled - I need the outputs from them! Device manager is showing both the Intel(R) HD Graphics 4600 and my new Nvidia GeForce GTX 1050Ti - just for some reason the outputs on the intel outputs are still not working (can be logged in fine - connect a monitor to an output and it seems to turn off the monitor and sends me back to the login screen)

[Prométhée]

but I am asking you precisely, if you have these options, and if you activate this, it works

[JoeR131]

In bios i have the option to disable integrated video. If i do that, log in, check device manager then the only graphic card i see is my GTX, no intel. Plugging a monitor into the ports then does nothing at all (as opposed to the  flashing my home screen up before then pushing me back to the login page).
If it should be in the same area - I do not have the option to adjust integrated graphics