About DDR Dual Channel and RAM Timings

Dual Channel Memory can help improve the RAM speed, because this technique doubles it. In order to use Dual Channel Memory, your motherboard has to be capable of supporting this technique and you will also need two equal memory modules. We'll explain this further, but first let's understand deeper the bottleneck problem.

Understanding RAM Timings
DDR and DDR2 memories follow the DDRxxx/PCyyyy classification.
The first number, xxx, indicates the maximum clock speed that the memory chips support. For instance, DDR400 memories work at 400 MHz at the most, and DDR2-667 can work up to 667 MHz. It is important to notice that this is not the real clock speed of the memory: the real clock of the DDR and DDR2 memories is half the labeled clock speed. This way, in fact, DDR400 memories work at 200 MHz and DDR2-667 memories work at 333 MHz.
The second number indicates the maximum transfer rate that the memory reaches, in MB/s. DDR400 memories transfer data at 3,200 MB/s at the most, hence they are labeled as PC3200. DDR2-667 memories transfer data at 5,336 MB/s and they are labeled as PC2-5400. As you can see, we use the number “2” after “DDR” or “PC” to indicate that we are talking about DDR2 memory, not DDR.

The maximum transfer rate for a memory module can be calculated thru the following formula:
Maximum Theoretical Transfer Rate = clock x number of bits / 8

For the average user, that is everything that we have to know about DDR/DDR2 memories. For the advanced user, there is yet another characteristic: the temporization of the memory, a.k.a. timings or latency. Let’s talk about it.

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