No video on RTX 2080 ti

[Faallen]

Hey guys, hope you are having a nice day, unlike my friend. He bought a new ASUS RTX 2080 ti Turbo. When he installed it there was no video output (HDMI and DP were tested), and that's when he called me.

His system is a pre-build DELL:
CPU: i7-8700
Mobo: Dell Inc. 0P0V56

RAM: 16GB
PSU: 860W

OS: Windows 10, latest version, and latest drivers from Nvidia were installed.

He was previously using GTX Titan X and the PC is still booting as normal if that GPU is installed.

With the RTX installed there is video output from the onboard GPU, but the RTX is not shown in Task Manager, and MSI Afterburner. 

In the BIOS I can see the card.
We tried to install the RTX on another PC and it booted as expected.

Has anyone experienced something similar or have any idea how to fix this? 
Any help is appreciated.
 

[GenericFanboy]

Drivers updated/installed?

 

[Faallen]

3 minutes ago, GenericFanboy said:

Drivers updated/installed?

 

Yes, the latest drivers were installed before the first attempt to connect the GPU. We removed all Nvidia drivers and installed them again. Also with all drivers removed we still couldn't get any output. Also we are not able to install drivers with the RTX card connected, the only output is through the onboard Display Port.

[nick name]

All power cables used and seated well?

[Faallen]

4 minutes ago, nick name said:

All power cables used and seated well?

Yes, the same cables deliver power to the Titan X.

In more news, we used a boot drive with Windows from the other computer and it it worked. Then we installed a fresh copy of Windows on the computer and the problems remained the same, no video output from the GPU, only from the onboard.