DisplayLink, maker of semiconductors that allow computers to connect to more than one monitor through USBs, has brought in $8 million in a fourth round of venture funding, according to an SEC filing. The Palo Alto, Calif. company did not list investors in the recent round, though it previously received financing from Atlas Venture, Balderton Capital, DAG Ventures and DFJ Esprit. It has raised $51 million to date.