4GB ( 1x 4GB Module ) DDR3 1333 MHz ( PC3-10600 ) DDR3 DIMM ( 240-Pin ) ECC UDIMM ( ECC Unbuffered DIMM ) 1.35V - DDR3 Low Voltage Compatible Equivalent for HP 647657-071, 647907-B212, 664695-001, 619488-B21, 647907-S21, NL797AA, 647907-B21 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