A memory daughter card (MDC) is described, having a very high-speed serial interface and an on-card MDC test engine that allows one MDC to be directly connected to another MDC for testing purposes. In some embodiments, a control interface allows the test engine to be programmed and controlled by a test controller on a test fixture that allows simultaneous testing of a single MDC or one or more pairs of MDCs, one MDC in a pair (e.g., the “golden” MDC) testing the other MDC of that pair. Other methods are also described, wherein one MDC executes a series of reads and writes and other commands to another MDC to test at least some of the other card's functions, or wherein one port executes a series of test commands to another port on the same MDC to test at least some of the card's functions.