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 64GB UPGRADE: Consists of a single 64GB DDR5 4800 PC5-38400 CL40 2Rx4 288-pin 1.1V ECC Registered DIMM Memory RAM Module Upgrade compatible with ThinkStation models P7 And PX. 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 Lenovo part numbers 4X71M22550 4X77A77032 4X77A77033 4X77A81441 4X77A81442.