Memory is installed on one or two HP Cell Boards, each having sixteen DIMM slots divided into quads. DIMMs must be installed as paired sets into specific slots on the Cell Board. Each pair is called an echelon, and DIMMs within an echelon must be of the same capacity. DIMM slots are arranged and numbered by echelon. For example, DIMM slots 0A and 0B comprise echelon 0, DIMM slots 1A and 1B comprise echelon 1, and so forth. The minimum memory capacity is 2GB per Cell Board, configured as 2 x 1GB DIMMs and installed in echelon 0. DIMMs of different capacities are supported by the largest capacity DIMMs must be installed first across a Cell, followed by progressively smaller capacities. For best performance, a Cell should be configured with a multiple of 8 DIMMs (4 pairs) and the memory loaded equally across Cell boards.