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'{{distinguish|Interleaved memory}} {{expand German|date=March 2018}} {{multiple issues| {{confusing |date=October 2011}} {{refimprove|date=January 2014}} }} In the fields of [[digital electronics]] and [[computer hardware]], '''multi-channel memory architecture''' is a technology that increases the data transfer rate between the [[DRAM]] memory and the [[memory controller]] by adding more channels of communication between them. Theoretically this multiplies the data rate by exactly the number of channels present. Dual-channel memory employs two channels. The technique goes back as far as the 1960s having been used in [[IBM System/360 Model 91]] and in [[CDC 6600]].<ref name="JacobNg2007">{{cite book| first1=Bruce | last1 = Jacob | first2 = Spencer | last2 = Ng | first3=David | last3 = Wang|title= Memory systems: cache, DRAM, disk|year = 2007 | publisher = Morgan Kaufmann|isbn=978-0-12-379751-3|page= 318}}</ref> Modern high-end processors like the [[Intel]] i7 Extreme and [[AMD]] Ryzen Threadripper series, along with various [[Xeon]]s support quad-channel memory. In March 2010, AMD released [[Socket G34]] and Magny-Cours Opteron 6100 series<ref name = Opteron6100>{{cite web | publisher = AMD | title = Opteron 6000 Series Platform Quick Reference Guide | url = http://sites.amd.com/us/documents/48101a_opteron%20_6000_qrg_rd2.pdf | accessdate = 2012-10-15 | format = [[PDF]]}}</ref> processors with support for quad-channel memory. In 2006, Intel released chipsets that support quad-channel memory for its [[LGA771]] platform<ref>{{Citation | url = http://ark.intel.com/products/27746/Intel-5000P-Memory-Controller | publisher = Intel | title = 5000P memory controller}}.</ref> and later in 2011 for its [[LGA2011]] platform.<ref>{{Citation | url = http://www.techpowerup.com/138087/Intel-LGA2011-Socket-X68-Express-Chipset-Pictured.html | title = Intel LGA2011 socket x68 express chipset pictured | publisher = Tech power up}}.</ref> Microcomputer chipsets with even more channels were designed; for example, the chipset in the [[AlphaStation]] 600 (1995) supports eight-channel memory, but the [[backplane]] of the machine limited operation to four channels.<ref>{{Citation | journal = HP | url = http://www.hpl.hp.com/hpjournal/dtj/vol7num1/vol7num1art7.txt | title = The Design and Verification of the AlphaStation 600 5-series Workstation | volume = 7 | number = 1 | author1 = John H. Zurawski | author2 = John E. Murray | author3 = Paul J. Lemmon}}.</ref> <!-- TODO: Cite a machine where they actually used 8 channels. --> == Dual-channel architecture == [[File:Dual channel slots.jpg|right|thumb|Dual channel memory slots, color-coded orange and yellow for this particular motherboard.]] Dual-channel-enabled memory controllers in a PC system architecture utilize two 64-bit data channels. Dual channel should not be confused with [[double data rate]] (DDR), in which data exchange happens twice per DRAM clock. The two technologies are independent of each other, and many motherboards use both by using DDR memory in a dual-channel configuration. === Operation === Dual-channel architecture requires a dual-channel-capable motherboard and two or more [[DDR SDRAM|DDR]], [[DDR2 SDRAM|DDR2]], [[DDR3 SDRAM|DDR3]], or [[DDR4 SDRAM|DDR4]] memory modules. The memory modules are installed into matching banks, which are usually color-coded on the [[motherboard]]. These separate channels allow the memory controller access to each memory module. Identical memory modules are not required, but are often recommended for best dual-channel operation. Motherboards supporting dual-channel memory layouts typically have color-coded [[DIMM]] sockets. Coloring schemes are not standardized and have opposing meanings, depending on the motherboard manufacturer's intentions and actual motherboard design. Matching colors may either indicate that the sockets belong to the same channel (meaning that DIMM pairs should be installed to differently colored sockets), or they may be used to indicate that DIMM pairs should be installed to the same color (meaning that each socket of the same color belongs to a different channel). The motherboard's manual will provide an explanation of how to install memory for that particular unit. A matched pair of memory modules may usually be placed in the first bank of each channel, and a different-capacity pair of modules in the second bank.<ref name= "Kingston520DDR">{{cite web | publisher = Infineon Technologies North America and Kingston Technology |date=September 2003 | url = http://www.kingston.com/newtech/MKF_520DDRwhitepaper.pdf | archiveurl = https://web.archive.org/web/20110929024052/http://www.kingston.com/newtech/MKF_520DDRwhitepaper.pdf | title = Intel Dual-Channel DDR Memory Architecture White Paper | edition = Rev. 1.0 | format = PDF, 1021&nbsp;[[kilobyte|KB]] | accessdate = 2007-09-06 | archivedate = 2011-09-29}}</ref> Modules rated at different speeds can be run in dual-channel mode, although the motherboard will then run all memory modules at the speed of the slowest module. Some motherboards, however, have compatibility issues with certain brands or models of memory when attempting to use them in dual-channel mode. For this reason, it is generally advised to use identical pairs of memory modules, which is why most memory manufacturers now sell "kits" of matched-pair DIMMs. Several motherboard manufacturers only support configurations where a "matched pair" of modules are used. A matching pair needs to match in: * Capacity (e.g. 1024&nbsp;MiB). Certain Intel chipsets support different capacity chips in what they call Flex Mode: the capacity that can be matched is run in dual-channel, while the remainder runs in single-channel. * Speed (e.g. PC5300). If speed is not the same, the lower speed of the two modules will be used. Likewise, the higher latency of the two modules will be used. * Same CAS Latency (CL) or Column Address Strobe. * Number of chips and sides (e.g. two sides with four chips on each side). * Matching size of rows and columns. Dual-channel architecture is a technology implemented on motherboards by the motherboard manufacturer and does not apply to memory modules. Theoretically any matched pair of memory modules may be used in either single- or dual-channel operation, provided the motherboard supports this architecture. === Performance === Theoretically, dual-channel configurations double the memory bandwidth when compared to single-channel configurations. This should not be confused with [[double data rate]] (DDR) memory, which doubles the usage of DRAM bus by transferring data both on the rising and falling edges of the memory bus clock signals. [[Tom's Hardware]] found little significant difference between single-channel and dual-channel configurations in synthetic and gaming benchmarks (using a "modern (2007)" system setup). In its tests, dual channel gave at best a 5% speed increase in memory-intensive tasks.<ref>{{Citation | url = http://www.tomshardware.com/reviews/PARALLEL-PROCESSING,1705-15.html | title = Parallel Processing | chapter = Part 2: RAM and HDD | publisher = Tom's Hardware}}.</ref> Another comparison by Laptop logic resulted in a similar conclusion for integrated graphics.<ref>{{Citation | url = http://laptoplogic.com/resources/detail.php?id=20 | title = Intel's Sonoma Platform: Dual Channel Performance | publisher = Laptop logic}}.</ref> The test results published by Tom's Hardware had a discrete graphics comparison. Another benchmark performed by [[TweakTown]], using [[SiSoftware]] Sandra, measured around 70% increase in performance of a quadruple-channel configuration, when compared to a dual-channel configuration.<ref name="tweaktown-banchmark">{{cite web | url = http://www.tweaktown.com/articles/4416/intel_x79_quad_channel_and_z68_dual_channel_memory_performance_analysis/index.html | title = Intel X79 Quad Channel and Z68 Dual Channel Memory Performance Analysis | date = 2011-11-16 | accessdate = 2013-11-30 | author = Shawn Baker | publisher = [[TweakTown]] }}</ref>{{rp|p. 5}} Other tests performed by TweakTown on the same subject showed no significant differences in performance, leading to a conclusion that not all benchmark software is up to the task of exploiting increased parallelism offered by the multi-channel memory configurations.<ref name="tweaktown-banchmark" />{{rp|p. 6}} === {{Anchor|GANGED}}Ganged versus unganged === Dual-channel was originally conceived as a way to maximize memory throughput by combining two 64-bit buses into a single 128-bit bus.{{disputed-inline|date=May 2018}}{{fact|date=May 2018}} This is retrospectively called the "ganged" mode. However, due to lackluster performance gains in consumer applications,<ref>{{Cite web | url = http://ixbtlabs.com/articles3/cpu/amd-phenom-x4-9850-ganged-unganged-p1.html | title = AMD Phenom X4 Memory Controller in the Ganged/ Unganged Mode | date = 2008-08-16 | accessdate = 2014-01-09 | website = ixbtlabs.com }}</ref> more modern implementations of dual-channel use the "unganged" mode by default, which maintains two 64-bit memory buses but allows independent access to each channel, in support of [[Multithreading (computer architecture)|multithreading]] with [[multi-core processor]]s.<ref name="ilsistemista-phenom">{{Cite web | url = http://www.ilsistemista.net/index.php/hardware-analysis/3-the-phenom-phenomii-memory-controller-and-the-ganged-vs-unganged-question.html?start=1 | title = The Phenom / PhenomII memory controller: ganged vs unganged mode benchmarked | date = 2010-06-17 | accessdate = 2014-01-09 | author = Gionatan Danti | website = ilsistemista.net }}</ref><ref name="amd-bkdg-10h">{{Cite web | url = http://support.amd.com/TechDocs/31116.pdf | title = BIOS and Kernel Developer's Guide (BKDG) For AMD Family 10h Processors | format = PDF | pages = 107–108 | date = 2013-01-11 | accessdate = 2014-01-09 | website = amd.com | quote = When the DCTs are in ganged mode, as specified by [The DRAM Controller Select Low Register] F2x110 [DctGangEn], then each logical DIMM is two channels wide. Each physical DIMM of a 2-channel logical DIMM is required to be the same size and use the same timing parameters. Both DCTs must be programmed with the same information (see 2.8.1 [DCT Configuration Registers]). When the DCTs are in unganged mode, a logical DIMM is equivalent to a 64-bit physical DIMM and each channel is controlled by a different DCT. Typical systems are recommended to run in unganged mode to benefit from the additional parallelism generated by using the DCTs independently. See 2.12.2 [DRAM Considerations for ECC] for DRAM ECC implications of ganged and unganged mode. Ganged mode is not supported for S1g3, S1g4, ASB2, and G34 processors.}}</ref> "Ganged" versus "unganged" difference could also be envisioned as an analogy with the way [[RAID 0]] works, when compared to [[JBOD]].<ref>{{Cite web | title = JBOD (just a bunch of disks or just a bunch of drives) | url = http://searchstorage.techtarget.com/definition/JBOD | date = September 2005 | accessdate = 2014-01-09 | first = Margaret | last = Rouse | website = SearchStorage.TechTarget.com }}</ref> With RAID&nbsp;0 (which is analogous to "ganged" mode), it is up to the additional logic layer to provide better (ideally even) usage of all available hardware units (storage devices, or memory modules) and increased overall performance. On the other hand, with JBOD (which is analogous to "unganged" mode) it is relied on the statistical usage patterns to ensure increased overall performance through even usage of all available hardware units.<ref name="ilsistemista-phenom" /><ref name="amd-bkdg-10h" /> == Triple-channel architecture == === Operation === [[DDR3]] triple-channel architecture is used in the [[Intel]] [[Core i7]]-900 series (the Intel Core i7-800 series only support up to dual-channel). The LGA 1366 platform (e.g. Intel X58) supports DDR3 triple-channel, normally 1333 and 1600Mhz, but can run at higher clock speeds on certain motherboards. AMD Socket AM3 processors do not use the DDR3 triple-channel architecture but instead use dual-channel DDR3 memory. The same applies to the Intel Core i3, [[Core i5]] and Core i7-800 series, which are used on the [[LGA 1156]] platforms (e.g., [[Intel P55]]). According to Intel, a Core i7 with DDR3 operating at 1066&nbsp;MHz will offer peak data transfer rates of 25.6&nbsp;GB/s when operating in triple-channel [[interleaved memory|interleaved]] mode. This, Intel claims, leads to faster system performance as well as higher performance per watt.<ref>{{Citation | publisher = Intel | title = X58 Product Brief |url= http://www.intel.com/Assets/PDF/prodbrief/x58-product-brief.pdf | format = PDF}}</ref> When operating in triple-channel mode, [[memory latency]] is reduced due to interleaving, meaning that each module is accessed sequentially for smaller bits of data rather than completely filling up one module before accessing the next one. Data is spread amongst the modules in an alternating pattern, potentially tripling available memory bandwidth for the same amount of data, as opposed to storing it all on one module. The architecture can only be used when all three, or a multiple of three, memory modules are identical in capacity and speed, and are placed in three-channel slots. When two memory modules are installed, the architecture will operate in dual-channel architecture mode.<ref name="support.intel.com">{{Citation | title = Desktop Boards – Triple Memory Modules | publisher = Intel | url= http://support.intel.com/support/motherboards/desktop/sb/CS-011965.htm#triple}}</ref> === Supporting processors === {{Col-begin|width=100%}} {{Col-break}} '''Intel Core i7:''' * Intel Core i7-9xx Bloomfield, Gulftown * Intel Core i7-9x0X Gulftown {{Col-break}} '''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-EP<ref>{{cite web | publisher =Intel |title= Core i7 Family Product Comparison | url =http://ark.intel.com/Compare.aspx?ids=48139,43559,43560,43562,43563,49666,47700,49654,50022,49158,49664,43122,49024,43124,43125,54616,52231,54610,52219,53463,54611,54615,53472,50067,52227,43126,43127,52237,41316,41318,41315,48498,48499,48500,37147,41447,37148,37150,37151,47933,52213,52214,52215,37149,37153,47932,52585, |at=Memory Specifications: # of Memory Channels}}</ref><ref>{{cite web | publisher =Intel |title= Xeon Family Product Comparison |url = http://ark.intel.com/Compare.aspx?ids=49942,49943,49944,49945,49946,27076,33103,27077,27078,27099,27080,28014,28015,27100,27093,27094,27101,28016,28017,27083,27084,27102,27085,28018,27086,27087,27088,28019,27089,27103,27091,27092,27097,27259,27293,27294,27260,27295,27296,27262,27263,27297,27298,27264,27299,27265,27266,27300,27267,27268,27269,27270,27301,27271,27272,27302,27273,27303,27202,27274,27275,27304,27276,27277,27278,27279,27280,27289,27220,27222,29748,27291,29750,27203,27204,27205,30775,27206,27208,27209,27210,27211,28020,27212,27213,27214,27215,27216,27217,27218,27219,27224,27225,27226,27227,27281,27282,27283,27284,27285,27286,27287,27288,28029,34694,35429,33093,36593,34739,28030,28031,28443,28032,33079,33080,33927,33081,33082,33083,33084,33085,37092,37094,40711,37096,37100,40200,37103,37104,52584,52583,52582,47925,47924,47923,48768,52581,46488,46489,30779,30780,30792,30793,30794,30795,36945,36939,36943,36941,46490,46491,46492,47642,47643,47640,47639,36892,32709,40481,47555,43233,36682,34738,35130,35574,29774,35129,29767,30791,34695,33090,33929,33091,40712,40726,40727,40201,41755,47928,48767,47927,48766,47926,31797,36935,36937,46493,46494,47646,47645,47644,47641,30778,30562,30563,30564,27223,39718,41313,39719,39720,39721,39722,39723,47918,47917,52586,37113,41643,28033,28034,30797,33931,35432,33932,33933,35433,41094,42927,42928,42929,42931,42932,48501,33907,36608,33908,28035,30702,34446,33087,35430,34447,33088,36893,37106,37109,37111,52580,47922,47921,47919,47920,52579,52577,47929,47916,52578,52576,46495,30796,36947,46497,46498,46499,52269,53401,52270,52271,52272,52273,52274,52275,52276,52277,52278,53568,53673,53674,53573,53570,53578,53569,53675,53676,53574,53571,53579,53677,53576,53575,53572,53577,53580, |at=Memory Specifications: # of Memory Channels}}</ref> * Intel Xeon x4xx v3 * Intel Pentium 14xx v3 * Intel Xeon x4xx v2 * Intel Pentium 14xx v2 * Intel Xeon x4xx * Intel Pentium 14xx {{col-end}} == Quad-channel architecture == === Operation === Quad-channel [[DDR4]] has replaced [[DDR3]] on the [[Intel X99]] [[LGA 2011]] platform, and is also used in AMD's [[Threadripper]] platform.<ref>[https://hothardware.com/news/amd-ryzen-threadripper-prey-4k-radeon-rx-vega-hits-in-july AMD Ryzen Threadripper And Vega Attack Prey At 4K, Quad GPUs Shred Blender, Radeon RX Vega Hits In July], "....with 16 cores and 32 threads with support for quad-channel DDR4 memory......"</ref> [[DDR3]] quad-channel architecture is used in the [[AMD]] [[Socket G34|G34]] platform and in the [[Intel X79]] [[LGA 2011]] platform. AMD processors for the [[Socket C32|C32]] platform and Intel processors for the [[LGA 1155]] platform (e.g., [[Intel Z68]]) use dual-channel DDR3 memory instead. The architecture can be used only when all four memory modules (or a multiple of four) are identical in capacity and speed, and are placed in quad-channel slots. When two memory modules are installed, the architecture will operate in a dual-channel mode; when three memory modules are installed, the architecture will operate in a triple-channel mode.<ref name="support.intel.com" /> === Supporting processors === {{Col-begin|width=100%}} {{Col-break}} '''AMD Ryzen:''' * Threadripper '''AMD Opteron:''' * Opteron 6100-series "Magny-Cours" (45&nbsp;nm)<ref name="Opteron6100"/> * Opteron 6200-series "Interlagos" (32&nbsp;nm)<ref name=Opteron6200>{{cite web | title = AMD Opteron 6200 Series Processor Quick Reference Guide | url = https://www.amd.com/us/Documents/Opteron_6000_QRG.pdf | format = PDF | accessdate = 2012-10-15 }}</ref> * Opteron 6300-series "Abu Dhabi" (32&nbsp;nm)<ref name=Opteron6300>{{cite web | title = AMD Opteron 6300 Series processor Quick Reference Guide | url = https://www.amd.com/us/Documents/Opteron_6300_QRG.pdf | format = PDF | accessdate = 2013-12-11 }}</ref> {{Col-break}} '''Intel Core:''' * Intel Core i9-7900X * Intel Core i7-7820X * Intel Core i7-7800X * Intel Core i7-6950X * Intel Core i7-6900K * Intel Core i7-6850K * Intel Core i7-6800K * Intel Core i7-5960X * Intel Core i7-5930K * Intel Core i7-5820K * Intel Core i7-4960X * Intel Core i7-4930K * Intel Core i7-4820K * Intel Core i7-3970X * Intel Core i7-3960X * Intel Core i7-3930K * Intel Core i7-3820 {{Col-break}} '''Intel Xeon:''' * Intel Xeon E5-x6xx v4 * Intel Xeon E7-x8xx v3 * Intel Xeon E5-x6xx v3 * Intel Xeon E7-x8xx v2 * Intel Xeon E5-x6xx v2 * Intel Xeon E7-x8xx * Intel Xeon E5-x6xx {{col-end}} == Six-channel architecture == Supported by [[Qualcomm Centriq]] server processors.<ref>{{cite news|last1=Kennedy|first1=Patrick|title=Qualcomm Centriq 2400 ARM CPU from Hot Chips 29|url=https://www.servethehome.com/qualcomm-centriq-2400-arm-cpu-hot-chips-29/|accessdate=14 November 2017|publisher=Serve The Home|date=23 August 2017}}</ref> Supported by Intel Xeon Scalable processors.<ref>https://www.intel.in/content/www/in/en/products/processors/xeon/scalable/bronze-processors/bronze-3106.html</ref> == Eight-channel architecture == Supported by [[AMD Epyc]] and [[Cavium#ThunderX2_SoCs|Cavium ThunderX2]] server processors.<ref>{{cite news|last1=Cutress|first1=Ian|title=AMD Prepares 32-Core Naples CPUs for 1P and 2P Servers: Coming in Q2|url=http://www.anandtech.com/show/11183/amd-prepares-32-core-naples-cpus-for-1p-and-2p-servers-coming-in-q2|accessdate=7 March 2017|publisher=Anandtech|date=7 March 2017}}</ref><ref>{{cite news|last1=Kennedy|first1=Patrick|title=Cavium ThunderX2 and OCP Platform Details|url=https://www.servethehome.com/cavium-thunderx2-ocp-platform-details/|accessdate=14 November 2017|publisher=Serve the Home|date=9 November 2017}}</ref> == See also == * [[List of device bandwidths]] * [[Lockstep (computing)]] == References == {{Reflist|30em}} == External links == * {{Citation | url = http://www.intel.com/support/motherboards/desktop/sb/cs-011965.htm | publisher = Intel | title = Desktop motherboards support | contribution = Single, dual, triple and flex memory modes}}. * [http://www.hardwaresecrets.com/everything-you-need-to-know-about-the-dual-triple-and-quad-channel-memory-architectures/ Everything You Need to Know About the Dual-, Triple-, and Quad-Channel Memory Architectures], November 2011, Hardware Secrets * [http://www.supermicro.com/support/resources/memory/X9_DP_memory_config.pdf Memory Configuration Guide for X9 Series DP Motherboards{{snd}} Revised Ivy Bridge Update (Socket R & B2)], January 2014, Super Micro Computer, Inc. * [https://web.archive.org/web/20130306122853/http://support.amd.com/us/kbarticles/Pages/ddr3memoryfrequencyguide.aspx DDR3 Memory Frequency Guide], May 2012, AMD (archived) <!-- Other languages have separate pages for dual/triple channel memory. --> <!-- The ones for triple channel are listed below. --> {{DEFAULTSORT:Multi-channel memory architecture}} [[Category:Computer memory]] [[Category:Intel x86 microprocessors]] [[ca:Dual channel]] [[de:Dual Channel]] [[de:Triple Channel]] [[es:Doble canal]] [[it:Dual channel]] [[ja:デュアルチャネル]] [[pl:Dual channel]]'