DIMMs come in a variety of ranks: dual or quad. The server supports 64-GB quad-rank (QR) Load-Reduced DIMMs (LRDIMMs) and 32-GB dual-rank (DR) and 16-GB DR Registered DIMMs (RDIMMs). Each DIMM is shipped with a label identifying its rank classification. The following table identifies the label corresponding to each DIMM rank classification:
Quad-rank LRDIMM: 4Rx4
Dual-rank RDIMM: 2Rx4