Is Dual Channel mode, or Dual Channel Memory, something that I need?
"Dual Channel Mode" is a feature that was created to reduce the potential performance bottleneck that exists between the CPU and the Memory Controller. It is enabled when a pair of same-size memory modules are installed into matching memory banks. These memory banks are usually colour coded on the motherboard, with each memory slot of the same colour code making up the 'channel'. I am yet to find any evidence to suggest that dual channel mode actually makes any difference at all to performance in productivity or gaming applications.
Unless specifically required in rare cases in some server applications, combining memory modules of different sizes in the same machine is compatible and will not affect system stability or reliability in any way. Whenever people ask me if they should worry about dual channel mode, I always say buy as much RAM as your budget and system needs require, and don't worry about dual channel mode. If you need 8GB of RAM and you can buy that in a single module that will work in your system, then it's better than buying 2x4GB of RAM as you usually end up with more total RAM installed, plus you are not throwing away any components in the bin.
What is Dual Channel DDR Memory?
There is a common misconception surrounding the term “dual channel DDR”. The same DDR memory modules that can be used in any DDR based system can be used in any dual channel system. Although referred to as “dual channel DDR memory”, it is the systems themselves that are released with either single memory channels or dual memory channels. Dual memory channel designs double the peak bandwidth over equivalent systems that only offer single memory channels. Many of the new systems released as “dual channel” allow the end user to run the system in either single channel OR dual channel memory mode.
Here is an example of how it works: In single channel memory systems, the memory modules are all installed on one channel, with only one access route to the memory controller (the official communicator between the installed memory and the rest of the system).
In dual channel memory systems, the memory modules are installed on two separate channels, each with its own access route to the memory controller, thus doubling the peak data bandwidth available.
What is Important to Know About Dual Channel DDR Memory Upgrades?
With very few exceptions, dual channel based systems can run in either single channel or dual channel mode. In order to take full advantage of the system running in dual channel mode, the memory modules need to be upgraded in like pairs. If you intend to fully utilise the dual channel features (or require other server-level features such as memory sparing or memory mirroring, then it's recommended that you purchase and install two like memory modules (one for channel A, and one for channel B) to insure like parts.
* If like speeds or like capacities (or the combination of both) are not installed, the system will automatically revert to single channel operation, regardless of module installation/configuration.
Some text is ©2004 Kingston Technology Company inc.
Additional information about dual channel mode can also be found on wikipedia.