This HP 647901-S21 compatible 16GB DDR3-1333MHz Dual Rank Registered ECC 1.35V 240-pin CL9 factory original RDIMM is 100% guaranteed to be compatible with your system and to work right the first time. Adding additional memory is the best way to increase the performance of your system. All our memory is built to strict JEDEC standards to meet or exceed the Tier 1 OEM's factory requirements. Our products are also guaranteed by federal law to not affect or void OEM warranties.

• 16 GB capacity is enough to execute all memory hungry programs simultaneously
• 240-pin-pin DDR3 SDRAM operates at an effective bus speed with minimal power consumption and as a result, you get optimal computer performance with an improved memory heat dissipation
• Up to 1333 MHz speed with Registered signal for playing the latest games and using heavy software