Dual-channel architecture DDR/DDR2/DDR3 SDRAM describes a motherboard technology that effectively doubles data throughput from RAM to the memory controller. Dual-channel-enabled memory controllers utilize two 64-bit data channels, resulting in a total bandwidth of 128-bits, to move data from RAM to the CPU.
The motherboard memory controller, which regulates data flow between CPU and the system memory (RAM), determines the types and speeds of RAM as well as the maximum size of each individual memory module and the overall memory capacity of the system. There are many memory controller designs. Prior to 2003, the most common was the single-channel configuration. Among its advantages are its low cost and flexibility. When the memory is unable to keep up with the processor, however, a bottleneck occurs, leaving the CPU with nothing to process. Under the single-channel architecture, any CPU with a bus speed greater than the memory speed would be liable to fall prey to this bottleneck effect.
The dual-channel configuration alleviates the problem by doubling the amount of available memory bandwidth. Instead of a single memory channel, a second parallel channel is added. With two channels working simultaneously, the bottleneck is reduced. Dual-channel architecture takes existing RAM technology and improves the method in which it is handled. While the actual implementation differs between Intel® and AMD motherboards, the basic theory stands.
In order to achieve this, two or more DDR/DDR2/DDR3 SDRAM memory modules must be installed into matching banks. These separate channels allow each memory module access to the memory controller, increasing throughput bandwidth. It is not required that identical modules be used, but this is often recommended for best compatibility for dual channel operation. It is possible to use a single-sided module of 512 MB and a double-sided module of 512 MB in dual-channel configuration, but how fast and stable it is depends on the memory controller.
Modules rated at different speeds can be run in dual-channel mode, although the motherboard will then run all memory modules at the speed of the slowest module. Some motherboards, however, have compatibility issues with certain brands or models of modules when attempting to use them in dual-channel mode. For this reason, it is generally advised to use identical pairs of memory modules. Several motherboard manufacturers only support configurations where a matched pair of modules are used.
Dual-channel architecture is a motherboard technology and does not apply to memory modules. In other words, any matched pair of memory modules may support single and dual-channel operation provided the motherboard supports this architecture.
A matched pair of memory modules consist of:
- Capacity (for example; 1024 MB). Certain Intel® chipsets support different capacity chips in what they call Flex Mode, the capacity that can be matched is run in dual channel the remainder runs single channel.
- Speed (for example; PC5300). If the speed is not the same, the lower speed of the two modules will be used. Likewise, the higher latency of the two modules will be used.
- Number of chips and sides (for example; 2 sides with 4 chips on each side).
Post from Acer Website: http://acer.custhelp.com/app/answers/detail/a_id/1664/~/what-is-dual-channel-memory%3F
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