DDR II

The difference between DDR II RAM and standard DDR RAM lies in its data buffers. Standard DDR RAM works by outputting two bits of data from the DRAM's I/O buffers onto the memory bus each clock cycle. This technology allows the RAM to operate at a speed twice that of a comparable SDRAM memory module.

In order to prevent memory corruption, memory timings control the amount of time that the memory banks are held open. The success of the DRAM's read and write function is entirely dependent upon the memory timings maintaining a steady pace. Specifically, data buffers on the DRAM modules buffer the input and output rates to and from the cells on the DRAM modules.

Doubling Up with DDR II

DDR II bandwidth runs at half the speed of the clock cycle. That means the data buffers can allow twice as many transfers to pass each clock cycle. With standard DDR, the data buffers run at the same speed as the clock and they process two transfers per cycle. With DDR II the data buffers run at half the speed of the clock, then, using DDR technology, double the transfer rate. They are, in essence, four times faster than comparable standard RAM.

DDR II is a relatively new technology. As such, it can be expensive and there are no guarantees that another technology will not soon supplant it as the industry standard. Still, for increased performance, DDR II is an excellent RAM choice.