Multi-channel memory architecture

Multi-channel anamnesis architectonics is a technology that increases the alteration acceleration of abstracts amid the DRAM and the anamnesis ambassador by abacus added channels of advice amid them. Apparently this multiplies the abstracts amount by absolutely the amount of channels present. Dual-channel anamnesis employs two channels which apparently doubles the abstracts alteration rate. The address goes aback as far as the 1960s accepting been acclimated in IBM System/360 Model 91 and in CDC 6600.1

Modern higher-end chipsets like the Intel i7-9x alternation and assorted Xeon chipsets abutment triple-channel memory. In 2011 Intel appear chipsets that abutment quad-channel anamnesis for their LGA2011 platform.2 Historically, microcomputer chipsets with even added channels had been designed. For example, the chipset in the AlphaStation 600 (1995) accurate eight-channel memory, but the backplane of the apparatus bound operation to four channels.3

Dual-channel architecture

Dual-channel-enabled anamnesis controllers in a PC arrangement architectonics advance two 64-bit abstracts channels. Dual approach should not be abashed with bifold abstracts amount (DDR), in which abstracts barter happens alert per DRAM clock. The two technologies are absolute of anniversary added and abounding motherboards use both, by application DDR anamnesis in a dual-channel configuration.

Operation

Dual-channel architectonics requires a dual-channel-capable motherboard and two or added DDR, DDR2 SDRAM, or DDR3 SDRAM anamnesis modules. The anamnesis modules are installed into analogous banks, which are usually blush coded on the motherboard. These abstracted channels acquiesce anniversary anamnesis bore admission to the anamnesis controller, accretion throughput bandwidth. It is not appropriate that identical modules be acclimated (if motherboard supports it), but this is about recommended for best dual-channel operation. It is accessible to use a single-sided bore of 512 MB4 and a double-sided bore of 512 MB in dual-channel configuration, but how fast and abiding it is depends on the anamnesis controller.

If the motherboard has two pairs of abnormally black DIMM sockets (the colors announce which coffer they accord to, coffer 0 or coffer 1), again one can abode a akin brace of anamnesis modules in coffer 0, but a different-capacity brace of modules in coffer 1, as continued as they are of the aforementioned speed. Using this scheme, a brace of 1 GB anamnesis modules in coffer 0 and a brace of akin 512 MB modules in coffer 1 would be adequate for dual-channel operation.5

Modules rated at altered speeds can be run in dual-channel mode, although the motherboard will again run all anamnesis modules at the acceleration of the slowest module. Some motherboards, however, accept affinity issues with assertive brands or models of anamnesis if attempting to use them in dual-channel mode. For this reason, it is about brash to use identical pairs of anamnesis modules, which is why a lot of anamnesis manufacturers now advertise "kits" of matched-pair DIMMs. Several motherboard manufacturers alone abutment configurations area a "matched pair" of modules are used. A analogous brace needs to bout in:

Accommodation (e.g. 1024 MB). Assertive Intel chipsets abutment altered accommodation chips in what they alarm Flex Mode: the accommodation that can be akin is run in dual-channel, while the butt runs in single-channel.

Acceleration (e.g. PC5300). If acceleration is not the same, the lower acceleration of the two modules will be used. Likewise, the college cessation of the two modules will be used.

Number of chips and abandon (e.g. two abandon with four chips on anniversary side).

Analogous admeasurement of rows and columns.

Dual-channel architectonics is a technology implemented on motherboards by the motherboard architect and does not administer to anamnesis modules. Theoretically any akin brace of anamnesis modules may be acclimated in either single- or dual-channel operation, provided the motherboard supports this architecture.

Purpose

Dual-channel technology was created to abode the affair of bottlenecks. Increased processor acceleration and achievement requires other, beneath arresting apparatus to accumulate pace. In the case of dual-channel design, the advised ambition is the anamnesis controller, which regulates abstracts breeze amid the CPU and arrangement anamnesis (RAM). The anamnesis ambassador determines the types and speeds of RAM as able-bodied as the best admeasurement of anniversary alone anamnesis bore and the all-embracing anamnesis accommodation of the system. However, if the anamnesis is clumsy to accumulate up with the processor, a aqueduct occurs, abrogation the CPU with annihilation to process. Under the single-channel architecture, any CPU with a bus acceleration greater than the anamnesis acceleration would be affected to this aqueduct effect.

The dual-channel agreement alleviates the botheration by acceleration the bulk of accessible anamnesis bandwidth. Instead of a individual anamnesis channel, a additional alongside approach is added. With two channels alive simultaneously, the aqueduct is reduced. Rather than delay for anamnesis technology to improve, dual-channel architectonics artlessly takes the absolute RAM technology and improves the adjustment in which it is handled. While the absolute accomplishing differs amid Intel and AMD motherboards, the basal approach stands.

Performance

There accept been capricious letters as to the achievement access of dual-channel configurations, with some tests citation cogent achievement assets while others advance about no gain.

Tom's Hardware begin little cogent aberration amid single-channel and dual-channel configurations in constructed and gaming benchmarks (using a "modern" arrangement setup). In its tests, bifold approach gave at best a 5% acceleration access in memory-intensive tasks.6 Another allegory by laptoplogic.com resulted in a agnate cessation for chip graphics.7 The analysis after-effects appear by Tom's Hardware had a detached cartoon comparison.

The aberration can be far added cogent in applications that dispense ample amounts of abstracts in memory. A allegory by TechConnect Magazine approved ample assets for dual-channel in tasks application block sizes greater than 4 MB, and during beck processing by the CPU.8dead link

Ganged versus unganged

Dual-channel was originally conceived as a way to aerate anamnesis throughput by accumulation two 64-bit buses into a individual 128-bit bus. This is retrospectively alleged the "ganged" mode. However, due to blah achievement assets in customer applications as discussed above, added avant-garde implementations of dual-channel use the "unganged" approach by default, which maintains two 64-bit anamnesis buses but allows absolute admission to anniversary channel, in abutment of multithreading with multi-core processors.

Triple-channel architecture

Operation

DDR3 triple-channel architectonics is acclimated in the Intel Core i7-900 alternation (the Intel Core i7-800 alternation alone abutment up to dual-channel), and the LGA 1366 belvedere (e.g., Intel X58). AMD Socket AM3 processors do not use the DDR3 triple-channel architectonics but instead use dual-channel DDR3 memory. The aforementioned applies to the Intel Core i3, Core i5 and Core i7-800 series, which are acclimated on the LGA 1156 platforms (e.g., Intel P55). According to Intel, a Core i7 with DDR3 operating at 1066 MHz will action aiguille abstracts alteration ante of 25.6 GB/s if operating in triple-channel interleaved mode. This, Intel claims, leads to faster arrangement achievement as able-bodied as college achievement per watt.9

When operating in triple-channel mode, anamnesis cessation is bargain due to interleaving, acceptation that anniversary bore is accessed sequentially for abate $.25 of abstracts rather than absolutely bushing up one bore afore accessing the next one. Abstracts is advance amidst the modules in an alternating pattern, potentially tripling accessible anamnesis bandwidth for the aforementioned bulk of data, as against to autumn it all on one module.

The architectonics can alone be acclimated if all three, or a assorted of three, anamnesis modules are identical in accommodation and speed, and are placed in three-channel slots. If two anamnesis modules are installed, the architectonics will accomplish in dual-channel mode.10

Supporting processors

Intel Core i7:

Intel Core i7-9xx Bloomfield, Gulftown

Intel Core i7-9x0X Gulftown

Intel Xeon:

Intel Xeon E55xx Nehalem-EP

Intel Xeon E56xx Westmere-EP

Intel Xeon ECxxxx Jasper Forest

Intel Xeon L55xx Nehalem-EP

Intel Xeon L5609 Westmere-EP

Intel Xeon L5630 Westmere-EP

Intel Xeon L5640 Westmere-EP

Intel Xeon LC55x8 Jasper Forest

Intel Xeon Wxxxx Bloomfield, Nehalem-EP, Westmere-EP

Intel Xeon X55xx Nehalem-EP

Intel Xeon X56xx Westmere-EP1112

Quadruple-channel architecture

Operation

DDR3 Quadruple-channel architectonics is acclimated in the AMD G34 belvedere and the Intel LGA 2011 belvedere (e.g., Intel X79). AMD processors which are acclimated on the C32 belvedere instead use dual-channel DDR3 memory. Intel processors which are acclimated on the LGA 1155 belvedere (e.g., Intel Z68) instead use dual-channel DDR3 memory.

The architectonics can alone be acclimated if all four, or a assorted of four, anamnesis modules are identical in accommodation and speed, and are placed in quad-channel slots. If two anamnesis modules are installed, the architectonics will accomplish in dual-channel mode. If three anamnesis modules are installed, the architectonics will accomplish in triple-channel mode.13

Supporting processors

Intel Core i7:

Intel Core i7-3960X

Intel Core i7-3930K

Intel Core i7-3820

Intel Xeon:

Intel Xeon E5-16xx

Intel Xeon E5-26xx