4.0GB OWC PC6400 DDR2 ECC 800MHZ 240-PIN FB-DIMM MEMORY MODOTHER WORLD COMPUTING OWC 4GB DDR2 SDRAM Memory Module 4 GB (1 x 4GB) DDR3 800 PC3 6400 DDR2 SDRAM 800 MHz CL5 1. 80 V ECC Fully Buffered 240 pin DIMM VPN: OWC64FBMP4GB SKU: RSC212702 UPC: 4 GB memory allows you to have more programs open at a time 800 MHz speed with Fully Buffered signal and CL5 latency to execute routine softwares at a steady pace DDR2 SDRAM interface multiplexes 2 bit data from memory cell and I O buses to minimize processor idle