64GB ( 1x 64GB Module ) DDR4 2666 MHz ( PC4-21300 ) DDR4 DIMM ( 288-Pin ) ECC LRDIMM ( Load Reduced DIMM ) 1.2V - DDR4 Standard Voltage Compatible Equivalent for HP 840759-191, 838085-K21, 815101-K21, 815101-S21, 838085-B21, 1XD87AA, 882449-001, 868844-001, 881901-B21, 840759-691 High performance Memory RAM upgrade designed for Server/Workstation Systems All modules undergo quality assurance testing to ensure dependable and reliable performance Please verify the supported memory (RAM) specifications of your system prior to purchase to ensure compatibility A-Tech provides a Lifetime Warranty for all orders & offers complimentary United States based Tech Support before, during, & after your purchase