OWC 64GB DDR4 2666MHz PC4-21300 CL19 1.2V 288pin Server DIMM ECC Registered memory compatible with Dell PowerEdge models C6420, R440, R540 and T440. 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. 100% COMPLIANT: With JEDEC-Standard specifications, ROHS Compliant, Warranty Safe Upgrade. Designed and Tested to Meet or Exceed all Manufacturer OEM Specs. 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. INDUSTRY LEADING: Consumer-friendly Advanced Replacement Program and Limited Lifetime Warranty, which includes Free Tech Support by Other World Computing.