16GB ( 1x 16GB Module ) DDR3 1333 MHz ( PC3-10600 ) DDR3 DIMM ( 240-Pin ) ECC RDIMM ( Registered DIMM ) 1.35V - DDR3 Low Voltage Compatible Equivalent for HP 687463-001, 647653-081, 647881-B21, 647883-S21 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