32GB Total. 4pcs 8GB DDR4, 2133MHz, ECC, CL15, 2R, X4, 1.2V, Registered, DIMM, 288-pin THIS MODULE IS MANUFACTURED BY Computer Memory Solutions LIFETIME WARRANTY BY Computer Memory Solutions Compatible with: HP/Compaq Apollo 4200 Gen9 (G9) Maximum Memory: 512 GB Reg ECC RDIMMs 1 TB LRDIMMs Expansions: 8 Socket(s) 16 Socket(s) Important: Memory will clock down to run at optimal speeds depending on processor model and number of modules installed. See latest ProLiant QuickSpecs for processor models and supported memory speeds. This system supports Registered ECC (RDIMM) or Load Reduced (LRDIMM) memory. Mixing RDIMM and LRDIMM is not supported within this system. If only one processor is installed, only 8 DIMM slots are available. When populating with two processors 16 DIMM slots are available.