ECC REGISTERED UPGRADE: This type of memory is used in Workstations and Servers. It will NOT be compatible with standard desktop computers. Also, it cannot be mixed with UNBUFFERED -or- ECC LOAD REDUCED memory. OWC 128GB UPGRADE: Consists of 2pcs of 64GB DDR4 2933 PC4-23400 CL21 2Rx4 288-pin 1.2V ECC Registered DIMM Memory RAM Module Upgrade compatible with Cisco models HX220c M5, HX240c M5, HXAF220c M5, HX-E-220M5SX And C480 ML M5. INDUSTRY LEADING: Consumer-friendly Advanced Replacement Program and Limited Lifetime Warranty, which includes Free Tech Support by Other World Computing. MAXIMIZE YOUR SERVER: With OWC's ECC Registered Server Memory, you will extend the life of your old infrastructure or save money when building a new one. Replacement for Cisco part numbers HXMRX64G2RTH, HXSPM64G2RTH, UCSMRX64G2RTH and UCSMRX64G2RTHS.