The Intel(R) Desktop Board DH55HC does not have on board graphics, the ports are available so that if you get a processor with a graphics controller built in to it you can use them. I quote from the motherboard information: "The board supports the Intel® Core™ i7, Intel® Core™ i5, Intel® Core™ i3, and Intel® Pentium® processors in the LGA1156 package. The board is featured with VGA, DVI-D and HDMI connectors and supports dual independent display for processors with Intel® Graphics Technology. "
You can check if your processor has an embedded graphics controller here:
Look for your processor model and it will tell you it has an embedded graphics controller.