Both drivers, from the Intel® HD Graphics and the third party video card need to be installed.
One thing I am curious about is, what is the version of Lucid Virtu that you are testing with?
Also, what video ports in the system are you using?
Keep in mind that the display/monitors need to be connected to either the integrated video ports or the ports in the video card, one or the other depending or the mode being used (i or d-mode), not on both.
To use Lucid VIRTU solution in d-Mode, display must be connected to discrete GPU installed in the system.
To use Lucid VIRTU solution in i-Mode, display must be always connected to motherboard video ports.
GPU drivers must be installed prior to Lucid VIRTU installation