DDR2 240-pin DDR2-SDRAM

DDR2 is an advanced type of DDR-RAM that allows much more data to be transferred in a given interval. Like DDR and SDRAM before it, DDR2 was launched out of the rapid advancements in graphics architecture, developed from a modified DDR technology introduced with NVIDIA's GeForce FX 5800 video card. Unlike DDR, which performs its read/write functions on the rise and fall of each system clock, DDR memory performs its read/write functions at half the rising and falling clock rate and supports much higher bus speeds than DDR, for a significant leap in computer performance.
The speed of DDR2 is measured in megahertz (MHz) and is available in a growing number of speeds ranging from, 200 MHz or PC2-3200 up to 400 MHz or PC2-8500 with faster speeds becoming available over time.