OWC 64GB DDR4 2933MHz PC4-23400 CL21 1.2V 288pin Server DIMM ECC Registered memory compatible with Lenovo ThinkAgile (Xeon SP Gen 2) models HX3520-G, HX3521-G, HX5520, HX5521 and HX7520. 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 memory. 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 4X70V98063, 4ZC7A08710 and 4ZC7A08744.