Many new Intel processors have got integrated Intel HD Graphics so that there is no need to have a separate graphics card in a system with such a processor. How is a display device, such as a monitor, connected to the integrated Intel HD Graphics? Can it be connected to a display device on a system without a separate graphics card, such as a desktop computer without a graphics card?
The 'adapter' device is sort-of absorbed into the chipset of the system.
Look at this Intel H67 chipset diagram as an example.
This is also stated in the Intel article extract after the diagram.
From Intel article Common Misconceptions of Intel® Processor Graphics,
I learned this via Do I need a GPU to use a built computer?: