The cord on the monitor attaches to your computer in the back. With onboard video, it will attach directly to the motherboard. If you have a videocard, it will stand up perpendicular to the motherboard, connected in a slot.
Open the case and look to see if the monitor attaches directly to the main motherboard, or if it attaches to a card standing up from the motherboard. Unplug the computer before opening it up and checking.