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Dual Channel DDR RAM:

When Dual Channel DDR Technology is activated, the bandwidth of Memory Bus will be double the original Memory Bus, with the fastest speed at 6.4GB/s DDR400. To activate Dual Channel DDR Memory, two DDR Memory Modules are inserted individually, one each into Channel A and Channel B.

If two DDR Memory Modules are inserted into the same Channel (DIMM 1,2,3 or DIMM 4,5,6) then Dual Channel Technology will operate ONLY as Single Channel Memory. Use Single Side Memory Modules and all Modules must be of equal values.

We never used nor advocated the use of RAMBUS Memory. Only DDR! And what does DDR stand for? Get it!

Serious, Dual Channel DDR is a function of the Memory Controller and NOT the RAM although achieving the intended throughput requires Two DDR Modules of the same RAM as explained in detail below.

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While recently inquiring with Crucial regarding Dual Channel DDR support we were informed, "There is no such thing as Dual Channel DDR. You need to read your manual of your motherboards and see if they support Dual Channel capability. For the Dual Channel capability, you need to install the matched pairs in the appropriate slots." Interesting response - IMO. We expected better. Shortly thereafter, The Crucial Insider - May 29, 2003 sent out 'The truth about Dual-Channel Memory' as follows:

 

Quoting Crucial, "DDR In-Depth: Dual Channel

The terminology "Dual-Channel DDR" is being misused by some in the Memory industry, which can mislead the Consumer. The fact is there's no such thing as Dual-Channel DDR Memory. There are, however, Dual-Channel Platforms. [Memory Controller]

When properly used, the term "Dual Channel" refers to the DDR chipset on certain Motherboards designed with Two Memory Channels instead of One. The Two Channels handle Memory-processing more efficiently by utilizing the theoretical Bandwidth of the Two Modules, thus reducing System Latencies, the Timing Delays that inherently occur with One Memory Module.

For example, One Controller reads and writes data while the Second Controller prepares for the next access, hence, eliminating the reset and setup delays that occur before One Memory Module can begin the read/write process all over again. Think of it like two relay runners.

The first runner runs one leg while the second runner sets up and prepares to receive the baton smoothly and carry on the task at hand without delay. While performance gains from Dual-Channel Chipsets aren't huge, they can increase Bandwidth by as much as 10 percent. To those seeking to push the performance envelope, that 10 percent can be very important.

So the next time you come across a product that's touted and sold as Dual-Channel DDR, know this: It's simply two DDR Memory Modules, packaged and marketed as a specialty product or a must-have "kit."

If indeed you have a Dual-Channel Platform and you want to take advantage of the performance gain it offers, our advice is to opt for high quality and service over expensive packaging, and simply purchase your DDR Memory in Pairs. However, be very careful to order Two Modules with the exact same Specifications; the Modules must be identical to each other to perform correctly." Thank you Crucial for that clarification.

So this Dual Channel terminology thing started with RAMBUS Memory and now Dual Channel Memory Interleaving from Intel has caught on with DDR Memory. Dual Channel Memory Interleaving was the term Intel used during our Intel Technical Solutions Training Summer 2003 in Houston, TX.

Our current hurdle seems to be Memory timings on Intel Motherboards. No problems with this situation on GigaByte MotherBoards. More later... As the plot thickens! For now - Enjoy! GB

  1. Kingston Technology Company - DDR Memory:
    1. Kingston Technology HyperX Memory Upgrades
  2. tech-report.com - Comments for A fix for Corsair memory with Intel's new chipsets - ja.zz: (6-17-03)
  3. images/bullet2.gifIntel Desktop Board - Single and Dual Channel Memory Modes: DDR

    Dual Channel memory configurations will provide increased performance over Single Channel configurations. Note: Memory channel speed is determined by the slowest DIMM module populated in the system.

    Rules to Enable Dual Channel Mode
    To achieve Dual Channel mode, the following conditions must be met:

    1. Matched DIMM configuration in each channel
    2. Same Density (128MB, 256MB, 512MB, etc.)
    3. Same DRAM technology (128Mb, 256Mb, or 512Mb)
    4. Same DRAM bus width (x8 or x16)
    5. All either single-sided or dual-sided
    6. Matched in both Channel A and Channel B memory channels
    7. Populate symmetrical memory slots (Slot 0 or Slot 1)
    Note: Configurations that do not match the above conditions will revert to Single Channel mode.

    The following conditions do not need to be met:
    1. Same brand
    2. Same timing specifications
    3. Same DDR speed
  4. Intel Desktop Board D865PERL - System Memory: Using Intel 865 Chipset.
  5. Intel Memory - DDR SDRAM System Validation Results: DDR400 Validation Testing.

Also notice Intel has NOT recommended using Memory Modules greater than 512 MB yet on Desktop Boards. Currently the highest capacity of Certified DDR Memory Modules are 512 MB (6/28/2003).

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Web Development, Gill Boyd & Team - Posted 06/17/2003; Updated 08/16/2005