DDR2 SDRAM is the second generation of DDR SDRAM.DDR2 SDRAM improves on DDR SDRAM by using differential signaling and lower voltages to support significant performance advantages over DDR SDRAM.Differential signaling requires additional contacts, so the number of contacts on a DDR SDRAM DIMM module was raised from 184 to 240.The voltage of DDR SDRAM DIMM's was lowered from 2.5V to 18.V. This improves power consumption and heat generation, as well as enabling more dense memory configurations for higher capacities.
DDR SDRAM is Double Data Rate SDRAM.DDR SDRAM is an improvement over regular SDRAM, also known as SDR SDRAM (Single Data Rate SDRAM).DDR SDRAM doubles the bandwidth of SDR DRAM by transferring data twice per cycle on both edges of the clock signal, implementing burst mode data transfer.
In electronic engineering, DDR3 SDRAM or double-data-rate three synchronous dynamic random access memory is a random access memory technology used for high speed storage of the working data of a computer or other digital electronic device.DDR3 is part of the SDRAM family of technologies and is one of the many DRAM (dynamic random access memory) implementations. DDR3 SDRAM is an improvement over its predecessor, DDR2 SDRAM.The primary benefit of DDR3 is the ability to run its I/O bus at four times the speed of the memory cells it contains, thus enabling faster bus speeds and higher peak throughput than earlier memory technologies. However, greater bus speed and throughput is achieved at the cost of higher latency. In addition, the DDR3 standard allows for chip capacities of 512 megabits to 8 gigabits, effectively enabling a maximum memory module size of 16 gigabytes.