Embodiments are generally directed to display controller testing through a high speed communications switch. An embodiment of an apparatus includes a display controller including a first test machine; a high speed switch coupled with the display controller; and one or more physical layer (PHY) logic elements including a first PHY with a second test machine, the first test machine and second test machine being replicas of each other at least in part. The first test machine and the second test machine are operable to synchronously lock with each other, the first test machine to generate a data sequence and transmit the data sequence to the second test machine, the second test machine to generate an expected data sequence and compare the expected data sequence to a received data sequence from the first test machine.