ECC LOAD REDUCED 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 REGISTERED memory. OWC 256GB UPGRADE: Consists of 4pcs of 64GB DDR4 2400 PC4-19200 CL17 4Rx4 288-pin 1.2V ECC Load Reduced DIMM Memory RAM Module Upgrade compatible with Cisco UCS models B420 M4 And C460 M4 (DDR4). 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 Load-Reduced Server Memory, you will extend the life of your old infrastructure or save money when building a new one. Replacement for Cisco part number UCSML1X644RVA.