The Difference Between DDR2 And DDR Memory Modules

Compared with DDR, the main improvement of DDR2 is that it can provide twice the bandwidth of DDR memory while maintaining the same memory module speed. This is mainly achieved by efficiently using two DRAM cores on each device. As a comparison, only one DRAM core can be used for DDR memory on each device. Technically speaking, there is still only one DRAM core on DDR2 memory, but it can be accessed in parallel, processing 4 data per access instead of two.
Combined with double speed data buffering, DDR2 memory can process up to 4 bits of data per clock cycle, which is twice as much as the 2 bits of data that traditional DDR memory can handle. Another improvement of DDR2 memory is that it uses FBGA packaging instead of traditional TSOP.
However, although DDR2 memory uses the same DRAM core speed as DDR, we still need to use a new motherboard to match DDR2 memory because the physical specifications of DDR2 are incompatible with DDR. Firstly, the interfaces are different. DDR2 has 240 pins, while DDR memory has 184 pins; Secondly, the VDIMM voltage of DDR2 memory is 1.8V, which is different from the 2.5V of DDR memory.