A parking-structure test system has motherboards that test memory modules. The motherboards are not stationary but are placed inside movable trays that move along conveyors. An unloader removes tested memory modules from test sockets on the motherboards, and a loader inserts untested memory modules into the motherboards using a robotic arm. A conveyor carries the motherboards from the loader to a parking and testing structure. An elevator raises or lowers the motherboards to different parking levels in the parking and testing structure. The motherboards move from the elevator to test stations on the parking level. A retractable connector from the test station makes contact with a motherboard connector to power up the motherboard, which then tests the memory modules. Test results are communicated from the test station to a host controller, which instructs the loader-unloader to sort the tested memory modules once the motherboard returns via the elevator and conveyors.