Dual channel memory technology is actually a kind of memory control and management technology, it depends on the chipset of memory controller work, in theory can make two the same specifications provided by memory bandwidth doubled. It has not any new technology, has been applied to the server and the workstation system, and just in order to solve the desktop increasingly distress memory bandwidth bottleneck problem it came to desktop motherboard technology front desk. In a few years ago, Intel company has launched a support toshiba satellite l505d-es5025 laptop cpu fan dual channel memory transmission technology i820 chipset, it and RDRAM memory constitute one pair of gold partner, played out and tribulations performance make it become the highlight of the market, but the production cost high flaws caused hurrah don't hit of the situation, was finally out by the market. Because of Intel has given in RDRAM has support, so at present the mainstream chipset double channel memory technology are refers to the dual channel DDR memory technology, mainstream dual channel memory platform Intel is Intel 910, 940, 945 series, and AMD aspects is NVIDIA Nforce2 series.
Dual channel memory technology is solve CPU bus bandwidth and memory bandwidth of the contradiction of low-priced, high performance scheme. Now CPU FSB (front end bus frequency) more and more high, Intel Pentium 4 than AMD Athlon XP to memory bandwidth is of much higher demand. Intel Pentium 4 processor and agp Data transmission using QDR (Quad Data Rate, four Data transmission) technology, the FSB is external clock 4 times. Intel Pentium 4 FSB respectively is 400, 533, 800 MHZ, bus bandwidth respectively is 3.2 GB/SEC, 4.2 GB/SEC and 6.4 GB/SEC, and DDR 266 / DDR 333 / DDR 400 can provide the memory bandwidth respectively is 2.1 GB/SEC, 2.7 GB/SEC and 3.2 GB/SEC. In the single channel memory mode, DDR memory cannot provide CPU need data bandwidth to become the performance of the system bottleneck.toshiba satellite l505d-es5024 laptop cpu fan While in double channel memory mode, double channel DDR 266, DDR 333, DDR 400 can provide the memory bandwidth respectively is 4.2 GB/SEC, 5.4 GB/SEC and 6.4 GB/SEC, here can see, double channel DDR 400 memory just can satisfy the 800 MHZ FSB Pentium 4 processor bandwidth demand. But to AMD Athlon XP platform is concerned, the processor and agp Data transmission technology USES DDR (Double Data Rate, Double Data transmission) technology, the frequency of the FSB is 2 times, its memory bandwidth demand far less than Intel Pentium 4 platform, the FSB is respectively 266, 333, 400 MHZ, bus bandwidth respectively is 2.1 GB/SEC, 2.7 GB/SEC and 3.2 GB/SEC, the use of single channel DDR 266, DDR 333, DDR 400 can meet its bandwidth demand, so in AMD K7 platform use dual channel DDR memory technology, convergence is not much, performance to improve is not such as Intel platform so obvious, the most obvious influence on the performance of or using integrated display chip integrated motherboard.
NVIDIA launched nForce chipset is the first person to turn the DDR memory interface expanded to 128 - bit chipset, then Intel in its E7500 server motherboard chipset also use the double channel DDR memory technology, SiS and VIA also in response, and actively developing this can make the DDR memory bandwidth has doubled since the technology. However, due to various reasons, in order to realize the dual channel DDR (128 bit parallel memory interface) transmission for many chipset makers is no easy task. DDR SDRAM memory and RDRAM memory completely different, the latter has the characteristics of high delay and for toshiba satellite l505d-109 laptop cpu fan serial transmission mode, these characteristics decide the design one support dual channel RDRAM memory chipset and difficulty of the cost is not too high. But DDR SDRAM memory but has its limitations, it itself is low delay characteristic, USES is the parallel transmission mode, and the most important thing: when the DDR SDRAM work frequency higher than 400 MHZ, the signal waveform will often appear distortion problem, all of these design one support dual channel DDR memory system chipset brings a lot of difficulty, chipset manufacturing cost will also improve accordingly, these factors are restricting the memory control technology development.
Ordinary single channel memory system has a 64 - bit memory controller, and double channel memory system have two 64 - bit memory controller, in double channel mode has 128 bit memory a wide, which in theory the memory bandwidth doubled. Although double 64 memory system provided by the bandwidth is equal to a 128 - bit memory system provided by the bandwidth, but both have effect is different. Dual channel system contains two independent, have complementary intelligent memory controller, theoretically speaking, two memory controller can in each other zero delay under the conditions of operation at the same time. For instance two memory controller, A for A, another for B. When controller B toshiba satellite l505-138 laptop cpu fan ready for the next access memory, the controller is A read/write main memory, and vice versa. Two memory controller such complementary "nature" can let the waiting time reduced by 50%. Dual channel DDR two memory controller on the function is exactly the same, and two controller timing parameters can be set separately programming. This flexibility allows a user to use two different structure, the capacity, the speed DIMM memory bank, the double channel DDR simply adjusting to a minimum memory standard to achieve 128 bit bandwidth, allowing different density/waiting time characteristics of the DIMM memory bank can reliably common operation.
Support dual channel DDR memory technology notebook chipset Intel platform have Intel 910, 915, 940, 945,, etc. Series.
Computer could support memory dual channel mainly depends on the toshiba satellite l505-11d laptop cpu fan mainboard chipset, support double channel chipset is described above, you can also view the mainboard chipset material. In addition some chipset in theory support different capacity of the memory bank realize double channel, but the actual or suggest use as far as possible parameter consistent two memory bank.
Memory double channel according to the general requirements on the mainboard memory slot color paired use, in addition some main board and in the BIOS do a Settings, general motherboard manual will have instructions. When the system has realized dual channel, some main board in the power on self test will there be prompt, can look at toshiba satellite l505-10j laptop cpu fan. Due to the self speed is faster, so can't see. So can use some software view, a lot of software can check, such as CPU - z, more compact. In the "memory" of a "channels" project, if here shows "Dual" such words, it means the has achieved double channel. Two 256 m memory constitute a dual channel the effect will be better than a 512 m memory effect is good, because a memory cannot constitute a dual channel.
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