On DDR Dual Channel configuration, memory is acessed 128 bits at a time, instead of 64 bits, which is the normal rate. Therefore, the transfer rate is doubled. In order to use this configuration on your PC, you need to have a motherboard with this feature and two identical memory modules correctly installed (same capacity and same speed – same manufacturer and same model is highly adviced). The installation is tricky because it is not just a matter of inserting the memory modules in any of the memory sockets available. We will be covering the installation on next page.

So, with Dual Channel the memory speed doubles as you can check on the table below.

Memory	Rated Clock	Maximum Transfer Rate	Dual Channel Maximum Transfer Rate
DDR200	200 MHz	1,600 MB/s	3,200 MB/s
DDR266	266 MHz	2,100 MB/s	4,200 MB/s
DDR333	333 MHz	2,700 MB/s	5,400 MB/s
DDR400	400 MHz	3,200 MB/s	6,400 MB/s
DDR2-400	400 MHz	3,200 MB/s	6,400 MB/s
DDR2-533	533 MHz	4,264 MB/s	8,528 MB/s
DDR2-667	667 MHz	5,336 MB/s	10,672 MB/s
DDR2-800	800 MHz	6,400 MBs	12,800 MB/s

With single channel configuration we were unable to match our 2.4 GHz Pentium 4 transfer rate of 4,264 MB/s, but with DDR Dual Channel we can match this speed by installing two DDR333 memory modules! You can go ahead and install DDR400 memories if you want to.

As for Pentium 4 CPUs with 800 MHz external bus, we need a 6,400 MB/s transfer rate and two DDR400 memory modules configured as Dual Channel are capable of giving that speed grade.

As we mentioned, if you want, you can install a memory configuration higher than required.