The 647893-B21 is another exceptional DDR3 memory module presented by HP, catered towards server applications demanding high reliability and performance. This module is characterized by its 4GB capacity, employing a 512Mx72 ECC Reg/RDIMM configuration that ensures data integrity through error correction while being registered to provide additional stability in server environments. It operates at DDR3-1333 speed (1333 MHz), suitable for systems supporting the PC3-10600 standard with a 240-pin connector. Notably, it operates at an energy-efficient voltage of 1.35V, crucial for servers where energy consumption directly impacts operational costs and thermal management. The HP 647893-B21 module represents an optimal upgrade for servers, aiming to enhance system reliability, performance, and power efficiency in a compact and well-engineered solution.