DDR2 doubles the bandwidth available to your system and runs twice as fast as regular DDR. DDR2 works very similar to DDR except that double the data bits are fetched internally to enable transferring the sequential data at twice the speed. Like DDR, the data is transferred on both the rising and falling edge of the clock cycle enabling DDR2 to literally double the data transfer rate of the original bus clock. For example; with DDR2 SDRAM, a memory running with a clock of 333 or 400MHz will yield an effective data rate of 667 or 800 mega-transfers per second (MTS), doubling the data rate.

DDR2 is a technology supported by a newer generation of DRAM controllers with DDR2 enabled logic. DDR2 DIMM modules are available in a variety of form factors including 240 pin full-sized DIMM, 200 pin So-DIMM, 240 pin Very Low Profile (VLP) DIMM, 244 pin Mini-DIMMs, and 240 pin FB-DIMMs. These form factors are not interchangeable with the preceding DDR or succeeding DDR3 technology form factors.