Hello, what is the difference between ddr2 pc2-6400 and ddr2 pc2-8500
pc2-6400 is ddr2 800mhz and pc2-8500 is ddr2 1066 (first one is slower than the second one)
ddr2 pc2-6400 is 800mhz and ddr2 pc2-8500 is 1066mhz. Slightly faster but you may have to customize your Bios to use the faster RAM. Also you won't notice much difference in real world, only in benchmarks...