DDR3 SDRAM

Double data rate type three SDRAM (DDR3 SDRAM) is a type of synchronous dynamic random-access memory (SDRAM) with a high bandwidth ("double data rate") interface, and has been in use since 2007. It is the higher-speed successor to DDR and DDR2 and predecessor to DDR4 synchronous dynamic random-access memory (SDRAM) chips. DDR3 SDRAM is neither forward nor backward compatible with any earlier type of random-access memory (RAM) because of different signaling voltages, timings, and other factors.

DDR3 is a DRAM interface specification. The actual DRAM arrays that store the data are similar to earlier types, with similar performance.

The primary benefit of DDR3 SDRAM over its immediate predecessor, DDR2 SDRAM, is its ability to transfer data at twice the rate (eight times the speed of its internal memory arrays), enabling higher bandwidth or peak data rates. With two transfers per cycle of a quadrupled clock signal, a 64-bit wide DDR3 module may achieve a transfer rate of up to 64 times the memory clock speed megahertz (MHz) in megabytes per second (MB/s). With data being transferred 64 bits at a time per memory module, DDR3 SDRAM gives a transfer rate of (memory clock rate) × 4 (for bus clock multiplier) × 2 (for data rate) × 64 (number of bits transferred) / 8 (number of bits/byte). Thus with a memory clock frequency of 100 MHz, DDR3 SDRAM gives a maximum transfer rate of 6400 MB/s.

DDR4 SDRAM

In computing, DDR4 SDRAM, an abbreviation for double data rate fourth generation synchronous dynamic random-access memory, is a type of synchronous dynamic random-access memory (SDRAM) with a high bandwidth ("double data rate") interface. Released to the market in 2014, it is one of the latest variants of dynamic random-access memory (DRAM), some of which have been in use since the early 1970s, and a higher-speed successor to the DDR2 and DDR3 technologies. It is not compatible with any earlier type of random access memory (RAM) due to different signaling voltages, physical interface and other factors.

DDR4 SDRAM was released to the public market in Q2 2014, focusing on ECC memory, while the non-ECC DDR4 modules became available in Q3 2014, accompanying the launch of Haswell-E processors that require DDR4 memory.

Features

The primary advantages of DDR4 over its predecessor, DDR3, include higher module density and lower voltage requirements, coupled with higher data rate transfer speeds. The DDR4 standard theoretically allows for DIMMs of up to 512 GiB in capacity, compared to the DDR3's theoretical maximum of 128 GiB per DIMM.

DDR2

DDR2 or DDRII may refer to: