When you use bios defaults and plug in a graphics card, the integrated graphics is disabled.
However if you run Lucid MVD software and enable Virtu Technology in the bios, it will be active even witha graphics card installed.
Also if you enable "IGD Multi monitor" in the bios (Bios->Settings-> Advanced-> Integrated Graphics Configuration).
Maybe you can check if you have enable any of those two settings in the bios.