Dual-channel mode of operative memory

I regret to admit that sometimes in the shops of computer equipment the buyer is not provided with exhaustive information on ways to improve the speed of the purchased computer. In part, this is quite understandable: for most tasks, the performance of modern components suffices with interest. However, an unpleasant residue remains, because a computer can work faster. So, what is a two-channel mode of memory is almost never reported.

Let's analyze the development trends: to replace the single-core processors came their multi-core counterparts; Dual Bios technology is increasingly used; There is RAID to combine multiple hard drives into a single array; Even two Ethernet network adapters are programmatically combined into one. This approach makes it relatively easy to increase productivity. The operational memory for which the dual-channel mode was proposed was not forgotten.

The term "bottleneck" in the computer field has appeared, in part, thanks to memory. With the growth of the processing power of the processors, it became clear that the speed that limits the overall speed of the system is the speed of the memory subsystem. The memory controller simply did not have time to process all CPU requests for data transfer in due time, because of which the last part of the time was idle, waiting for the next portion of data from the memory banks to be received. The solution was obvious - you need a dual-channel memory mode. To implement it, a corresponding additional controller has been added. As a result, it turned out that some of the memory slots were serviced by the first controller, and the other - by the second. Further everything is simple: the two-channel mode illustrates a well-known experiment with water poured from bottles. According to him, through two spouts per unit time passes more water than through one, whose diameter is equal to the sum of the first two. Dual-channel mode not only increased the throughput, but also reduced the load on each controller several times (and this is heating, the requirements for the element base, etc.). In modern CPUs, memory controllers are on the same chip as the cores. For comparison: before the controller was located in chipset chipset.

To use two-channel mode of operation of the RAM, you must connect at least two memory modules to the motherboard . If there are only two connectors, as on budget solutions, then there are no complications: we insert it modulo into each connector and get an increase in performance (theoretically 2 times, in practice the same - from 20 to 70%). With more connectors, you need to make the correct connection: the connectors do not vainly differ in color. To activate multichannel mode, the modules need to be connected to the connectors of the same color. It is also true that the connection to all connectors similarly includes multi-channel mode.

The main requirement for the correct operation of the two-channel mode is that the modules must be designed for the same frequency (1066, 1333, 1600), be of the same size, the same manufacturer and, preferably, the series. Some processor manufacturers (Intel) allow the use of modules of different sizes, for example, 512 MB and 1 GB. In this case, a special Flex mode is activated, in which two 512 MB blocks work in Dual Chanel, and "extra" 512 MB in single mode.

From all this, it follows a natural conclusion: when buying a computer, you need to purchase more than one memory module, and two, the total volume of which is equal to the capacity of one roomy module. For example, if you decide to buy 4 GB, then it's more rational to choose 2 × 2 GB.