Dual-channel memory technology is actually a kind of memory control and management technology. It relies on the function of the memory controller of the chipset to theoretically double the bandwidth provided by two memories of the same specification. It is not a new technology. It has been used in server and workstation systems for a long time. It only came to the foreground of desktop motherboard technology in order to solve the increasingly difficult memory bandwidth bottleneck problem of desktop computers. A few years ago, Intel introduced the i820 chipset that supports dual-channel memory transmission technology, which forms a pair of golden partners with RDRAM memory. The outstanding performance that it exerts makes it the biggest bright spot in the market, but the production cost The excessively high defect caused the situation of applauding and not applauding, and was finally eliminated by the market. Because Intel has given up support for RDRAM, the current dual-channel memory technology of mainstream chipsets refers to dual-channel DDR memory technology. The mainstream dual-channel memory platform Intel is the Intel 865 and 875 series, while AMD is NVIDIA Nforce2. series. Dual-channel memory technology is a low-cost, high-performance solution to resolve the conflict between CPU bus bandwidth and memory bandwidth. Now that the CPU's FSB (Front Side Bus Frequency) is getting higher and higher, Intel PenTIum 4 has much higher memory bandwidth requirements than AMD Athlon XP. The data transmission between the Intel PenTIum 4 processor and the Northbridge chip uses QDR (Quad Data Rate, four data transmission) technology, and its FSB is 4 times that of the external frequency. The FSB of Intel PenTIum 4 is 400, 533, 800MHz, the bus bandwidth is 3.2GB / sec, 4.2GB / sec and 6.4GB / sec, and the memory bandwidth provided by DDR 266 / DDR 333 / DDR 400 is 2.1 GB / sec, 2.7GB / sec and 3.2GB / sec. In the single-channel memory mode, DDR memory cannot provide the data bandwidth required by the CPU and becomes a performance bottleneck of the system. In the dual-channel memory mode, the dual-channel DDR 266, DDR 333, and DDR 400 can provide memory bandwidths of 4.2GB / sec, 5.4GB / sec, and 6.4GB / sec, respectively. As you can see here, the dual-channel DDR 400 memory just meets the bandwidth requirements of the 800MHz FSB PenTIum 4 processor. For the AMD Athlon XP platform, the data transmission technology of its processor and Northbridge chip uses DDR (Double Data Rate, double data transmission) technology, FSB is twice the external frequency, and its memory bandwidth requirements are far lower For the Intel Pentium 4 platform, the FSBs are 266, 333, and 400MHz, and the bus bandwidths are 2.1GB / sec, 2.7GB / sec, and 3.2GB / sec, which can be satisfied by using single-channel DDR 266, DDR 333, and DDR 400 Because of its bandwidth requirements, the use of dual-channel DDR memory technology on the AMD K7 platform can be said to have little effect. The performance improvement is not as obvious as the Intel platform. The most obvious impact on performance is the integrated motherboard with integrated display chip. The nForce chipset introduced by NVIDIA is the first to expand the DDR memory interface to 128-bit chipset, and then Intel also used this dual-channel DDR memory technology on its E7500 server motherboard chipset, SiS and VIA have also in response, the positive development of this technology allows DDR memory bandwidth doubling. However, for various reasons, to achieve this dual-channel DDR (128-bit parallel memory interface) transmission for many chipset manufacturers is no easy task. DDR SDRAM memory is completely different from RDRAM memory. The latter has the characteristics of high latency and serial transmission. These characteristics determine the difficulty and cost of designing a dual-channel RDRAM memory chipset. However, DDR SDRAM memory has its own limitations. It is low-latency. It uses a parallel transmission mode. The most important point is that when the DDR SDRAM operating frequency is higher than 400MHz, its signal waveform tends to be distorted. issues, which are designed to bring a dual-channel DDR memory system chipset no small difficulty, the manufacturing cost of the chipset will be a corresponding increase, these factors are restricting the development of this memory control technology. Ordinary single-channel memory system having a memory controller 64, and the dual-channel memory system has two 64-bit memory controller with bit wide 128bit memory in dual channel mode, whereby the memory bandwidth theoretically Double it. Although the dual 64-bit system memory bandwidth provided by the bandwidth equivalent to a 128-bit memory system is provided, but the effect was achieved both are different. The dual-channel system includes two independent, complementary intelligent memory controllers. In theory, both memory controllers can operate simultaneously with zero delay between each other. For example, two memory controllers, one for A and the other for B. When controller B is preparing for the next memory access, controller A is reading / writing the main memory and vice versa. This complementary "natural nature" of the two memory controllers can reduce the waiting time by 50%. The two memory controllers of the dual-channel DDR are identical in function, and the timing parameters of the two controllers can be individually programmed. This flexibility allows users to use two DIMMs with different configurations, capacities, and speeds. At this time, dual-channel DDR is simply adjusted to the lowest memory standard to achieve 128bit bandwidth, allowing DIMMs with different density / latency characteristics reliably work together.
Desktop chipsets that support dual-channel DDR memory technology. Intel platforms include Intel's 865P, 865G, 865GV, 865PE, 875P and later 915, 925 series; VIA's PT880, ATI's Radeon 9100 IGP series, and SIS's SIIS 655 , SIS 655FX and SIS 655TX; AMD platform, we have the KT880 VIA is, NVIDIA's nForce2 Ultra 400, nForce2 IGP, nForce2 SPP and later chips. AMD's 64-bit CPU, because of the integrated memory controller, so it depends on whether the CPU supports dual-channel memory. At present, AMD's desktop CPUs only support dual-channel memory for 939 interfaces, and dual-channel memory for 754 interfaces. In addition to AMD's 64-bit CPU, whether other computers can support dual-channel memory depends on the motherboard chipset. The chipset that supports dual channels is described above, and you can also view the motherboard chipset information. In addition, some chipsets theoretically support memory modules of different capacities to achieve dual channels, but in practice it is recommended to use two memory modules with the same parameters as much as possible. Generally requires the use of dual-channel memory according to the color on the motherboard memory slot pairs, in addition some have to do motherboard disposed about the BIOS, the description will explain the general board. After the system has implemented dual-channel, some motherboards will be prompted during power-on self-test, you can take a closer look. Since the self-test speed is relatively fast, it may not be visible. So you can use some software to view, many software can be checked, such as cpu-z, which is relatively small. There is a "channels" item in the "memory" item. If the word "Dual" is displayed here, it means that dual channels have been implemented. Two 256M memories constituting a dual-channel effect will be better than a 512M memory, because a single memory cannot constitute a dual channel. |