Forgot to mention your motherboard may be different and just have an option for PCI-E in bios
If you believe the on board graphics card is conflicting, go into the bios and check for a setting called primary video controller. and make sure the option is something like GFXO GPP IGFX PCI and not IGFX GFXO GPP PCI
The first 4 letter are the important ones.
GFXO = PCI-e graphics card
IGFX = integrated on-board graphics