A system performs automated at-speed testing of a plurality of devices that generate serial data signals having multiple gigabit per second baud rates. The system includes a test head including a device interface board (DIB), the DIB having a device under test holding device for coupling the devices to the DIB. The system also includes a rider board including a multiplexing system coupled to a control system and to the DIB, the rider board being configured to route a serial data test signal having multi-gigabit per second baud rate through one or more of the devices.