DDR2 started to become competitive with the older DDR standard by the end of 2004, as modules with lower latencies became available. DDR2-SDRAM is considered an evolutionary upgrade over existing DDR memory. It maintains the same core functions, transferring 64 bits of data twice every clock cycle for an effective transfer rate twice that of the front-side bus (FSB) of a computer system, and an effective bandwidth equal to its speed x 8.
DDR2 introduces some new features which allow it to ramp up to much higher speeds (with correspondingly higher bandwidth) and higher memory densities, all the while using less power. Sounds good doesn't it? Let's look at the 'big' facts first, before we explore the memory in detail. DDR2 memory uses a new form factor, a 240 pin DIMM (Dual Inline Memory Module) which is *not* compatible with current DDR memory slots. Upcoming chipsets by Intel and other manufacturers will support
DDR2 specifically, and are not backwards compatible. For use in computers, DDR2 SDRAM is supplied in DIMMs with 240 pins and a single locating notch. DIMMs are identified by their peak transfer capacity (often called bandwidth).
DDR3 is the next-generation, high-performance solution for CPU systems. DDR3 memory are twice as fast as today's highest speed DDR2 memory products. Select your DDR3 Memory from the following.
DDR2 Memory RAM
Note: DDR2-xxx denotes data transfer rate, and describes raw DDR chips, whereas PC2-xxxx denotes theoretical bandwidth (though it is often rounded up or down), and is used to describe assembled DIMMs. Bandwidth is calculated by taking transfers per second and multiplying by eight. This is because DDR2 memory modules transfer data on a bus that is 64 data bits wide, and since a byte comprises 8 bits, this equates to 8 bytes of data per transfer.
Some manufacturers label their DDR2 modules as PC2-4300 instead of PC2-4200, PC2-5400 instead of PC2-5300, and PC2-8600 instead of PC2-8500. At least one manufacturer has reported this reflects successful testing at a higher-than standard data rate, whilst others simply use the alternate rounding as the name, as described above.
What is DDR memory? | Why DDR Memory? | What DDR Memory to buy? | The Evolution of DDR, DDR2 and SDRAM | Fully Buffered DDR DDR2 DIMMS | Installing DDR Memory | RAM Influence on Computer Performance | Issues to consider before buying RAM | How Computer Memory Works? | How much RAM is enough? | DDR3 Memory RAM | Features of DDR3 Memory
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