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DDR3 SDRAM

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This article is about the computer main memory. For the graphics memory, seeGDDR3.For the mobile memory, seeLPDDR3.For the video game, seeDance Dance Revolution 3rdMix.

Double Data Rate 3 Synchronous Dynamic Random-Access Memory(DDR3 SDRAM) is a type ofsynchronous dynamic random-access memory(SDRAM) with a highbandwidth( "double data rate") interface, and has been in use since 2007. It is the higher-speed successor toDDRandDDR2and predecessor toDDR4synchronous dynamic random-access memory (SDRAM) chips. DDR3 SDRAM is neitherforwardnorbackward compatiblewith any earlier type ofrandom-access memory(RAM) because of different signaling voltages, timings, and other factors.

DDR3 SDRAM
Double Data Rate 3 Synchronous Dynamic Random-Access Memory
Type ofRAM
4 GB PC3-12800 ECC DDR3 DIMM
DeveloperJEDEC
TypeSynchronous dynamic random-access memory(SDRAM)
Generation3rd generation
Release date2007;17 years ago(2007)
Standards
  • DDR3-800 (PC3-6400)
  • DDR3-1066 (PC3-8500)
  • DDR3-1333 (PC3-10600)
  • DDR3-1600 (PC3-12800)
  • DDR3-1866 (PC3-14900)
  • DDR3-2133 (PC3-17000)
Clock rate400–1066 MHz
VoltageReference 1.5 V
PredecessorDDR2 SDRAM(2003)
SuccessorDDR4 SDRAM(2014)

DDR3 is a DRAM interface specification. The actual DRAM arrays that store the data are similar to earlier types, with similar performance. The primary benefit of DDR3 SDRAM over its immediate predecessor DDR2 SDRAM, is its ability to transfer data at twice the rate (eight times the speed of its internal memory arrays), enabling higher bandwidth or peak data rates.

The DDR3 standard permits DRAM chip capacities of up to 8gigabits(Gbit) (so 1 gigabyte by DRAM chip), and up to fourranksof 64 Gbit each for a total maximum of 16gigabytes(GB) per DDR3 DIMM. Because of a hardware limitation not fixed until Ivy Bridge-E in 2013, most older Intel CPUs only support up to 4-Gbit chips for 8 GB DIMMs (Intel's Core 2 DDR3 chipsets only support up to 2 Gbit). All AMD CPUs correctly support the full specification for 16 GB DDR3 DIMMs.[1]Intel, also supports 16 GB DIMMs, from Broadwell (also named as "AMD Only memory, because of using 11-bit addressing).

History

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In February 2005,Samsungintroduced the first prototype DDR3 memory chip. Samsung played a major role in the development and standardisation of DDR3.[2][3]In May 2005, Desi Rhoden, chairman of theJEDECcommittee, stated that DDR3 had been under development for "about 3 years".[4]

DDR3 was officially launched in 2007, but sales were not expected to overtake DDR2 until the end of 2009 or possibly early 2010, according to Intel strategist Carlos Weissenberg, speaking during the early part of their roll-out in August 2008.[5](The same timescale for market penetration had been stated bymarket intelligencecompany DRAMeXchange over a year earlier in April 2007,[6]and by Desi Rhoden in 2005.[4]) The primary driving force behind the increased usage of DDR3 has been newCore i7processors from Intel andPhenom IIprocessors from AMD, both of which have internal memory controllers: the former requires DDR3, the latter recommends it.IDCstated in January 2009 that DDR3 sales would account for 29% of the total DRAM units sold in 2009, rising to 72% by 2011.[7]

Successor

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Main article:DDR4 SDRAM

In September 2012,JEDECreleased the final specification of DDR4.[8]The primary benefits of DDR4 compared to DDR3 include a higher standardized range ofclock frequenciesanddata transfer rates[9]and significantly lowervoltage.

Specification

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Overview

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Physical comparison ofDDR,DDR2,and DDR3SDRAM
Desktop PCs (DIMM)
Notebook and convertible PCs (SO-DIMM)

Compared to DDR2 memory, DDR3 memory uses less power. Some manufacturers further propose using"dual-gate" transistorsto reduceleakageof current.[10]

According toJEDEC,[11]: 111 1.575 volts should be considered the absolute maximum when memory stability is the foremost consideration, such as in servers or other mission-critical devices. In addition, JEDEC states that memory modules must withstand up to 1.80 volts[a]before incurring permanent damage, although they are not required to function correctly at that level.[11]: 109 

Another benefit is itsprefetch buffer,which is 8-burst-deep. In contrast, the prefetch buffer of DDR2 is 4-burst-deep, and the prefetch buffer of DDR is 2-burst-deep. This advantage is an enabling technology in DDR3's transfer speed.

DDR3 modules can transfer data at a rate of 800–2133MT/s usingboth rising and falling edgesof a 400–1066 MHz I/Oclock.This is twice DDR2's data transfer rates (400–1066 MT/s using a 200–533 MHz I/O clock) and four times the rate of DDR (200–400 MT/s using a 100–200 MHz I/O clock). High-performance graphics was an initial driver of such bandwidth requirements, where high bandwidth data transfer betweenframebuffersis required.

Because thehertzis a measure ofcyclesper second, and no signal cycles more often than every other transfer, describing the transfer rate in units of MHz is technically incorrect, although very common. It is also misleading because variousmemory timingsare given in units of clock cycles, which are half the speed of data transfers.

DDR3 does use the same electric signaling standard as DDR and DDR2,Stub Series Terminated Logic,albeit at different timings and voltages. Specifically, DDR3 uses SSTL_15.[13]

In February 2005,Samsungdemonstrated the first DDR3 memory prototype, with a capacity of 512Mband a bandwidth of 1.066Gbps.[2]Products in the form of motherboards appeared on the market in June 2007[14]based onIntel'sP35 "Bearlake" chipsetwith DIMMs at bandwidths up to DDR3-1600 (PC3-12800).[15]TheIntel Core i7,released in November 2008, connects directly to memory rather than via a chipset. The Core i7, i5 & i3 CPUs initially supported only DDR3.AMD'ssocket AM3Phenom IIX4 processors, released in February 2009, were their first to support DDR3 (while still supporting DDR2 for backwards compatibility).

Dual-inline memory modules

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DDR3dual-inline memory modules (DIMMs)have 240 pins and are electrically incompatible with DDR2. A key notch—located differently in DDR2 and DDR3 DIMMs—prevents accidentally interchanging them. Not only are they keyed differently, but DDR2 has rounded notches on the side and the DDR3 modules have square notches on the side.[16]DDR3SO-DIMMshave 204 pins.[17]

For theSkylake microarchitecture,Intel has also designed a SO-DIMM package namedUniDIMM,which can use either DDR3 or DDR4 chips. The CPU's integrated memory controller can then work with either. The purpose of UniDIMMs is to handle the transition from DDR3 to DDR4, where pricing and availability may make it desirable to switch RAM type. UniDIMMs have the same dimensions and number of pins as regular DDR4 SO-DIMMs, but the notch is placed differently to avoid accidentally using in an incompatible DDR4 SO-DIMM socket.[18]

Latencies

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DDR3 latencies are numerically higher because the I/O busclockcycles by which they are measured are shorter; the actual time interval is similar to DDR2 latencies, around 10 ns. There is some improvement because DDR3 generally uses more recent manufacturing processes, but this is not directly caused by the change to DDR3.

CAS latency (ns) = 1000 × CL (cycles) ÷ clock frequency (MHz) = 2000 × CL (cycles) ÷ transfer rate (MT/s)

While the typicallatenciesfor a JEDEC DDR2-800 device were 5-5-5-15 (12.5 ns), some standard latencies for JEDEC DDR3 devices include 7-7-7-20 for DDR3-1066 (13.125 ns) and 8-8-8-24 for DDR3-1333 (12 ns).

As with earlier memory generations, faster DDR3 memory became available after the release of the initial versions. DDR3-2000 memory with 9-9-9-28 latency (9 ns) was available in time to coincide with the Intel Core i7 release in late 2008,[19]while later developments made DDR3-2400 widely available (with CL 9–12 cycles = 7.5–10 ns), and speeds up to DDR3-3200 available (with CL 13 cycles = 8.125 ns).

Power consumption

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Power consumption of individual SDRAM chips (or, by extension, DIMMs) varies based on many factors, including speed, type of usage, voltage, etc. Dell's Power Advisor calculates that 4 GB ECC DDR1333 RDIMMs use about 4 W each.[20]By contrast, a more modern mainstream desktop-oriented part 8 GB, DDR3/1600 DIMM, is rated at 2.58 W, despite being significantly faster.[21]

Modules

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List of standard DDR3 SDRAM modules
Name Chip Bus Timings
Standard Type Module Clock rate(MHz) Cycle time(ns)[22] Clock rate(MHz) Transfer rate(MT/s) Bandwidth(MB/s) CL-TRCD-TRP CAS latency(ns)
DDR3-800 D PC3-6400 100 10 400 800 6400 5-5-5 12.5
E 6-6-6 15
DDR3-1066 E PC3-8500 1331⁄3 71⁄2 5331⁄3 10662⁄3 85331⁄3 6-6-6 11.25
F 7-7-7 13.125
G 8-8-8 15
DDR3-1333 F* PC3-10600 1662⁄3 6 6662⁄3 13331⁄3 106662⁄3 7-7-7 10.5
G 8-8-8 12
H 9-9-9 13.5
J* 10-10-10 15
DDR3-1600 G* PC3-12800 200 5 800 1600 12800 8-8-8 10
H 9-9-9 11.25
J 10-10-10 12.5
K 11-11-11 13.75
DDR3-1866 J* PC3-14900 2331⁄3 42⁄7 9331⁄3 18662⁄3 149331⁄3 10-10-10 10.56
K 11-11-11 11.786
L 12-12-12 12.857
M* 13-13-13 13.929
DDR3-2133 K* PC3-17000 2662⁄3 33⁄4 10662⁄3 21331⁄3 170662⁄3 11-11-11 10.313
L 12-12-12 11.25
M 13-13-13 12.188
N* 14-14-14 13.125

* optional

DDR3-xxx denotes data transfer rate, and describes DDR chips, whereas PC3-xxxx denotes theoretical bandwidth (with the last two digits truncated), and is used to describe assembled DIMMs. Bandwidth is calculated by taking transfers per second and multiplying by eight. This is because DDR3 memory modules transfer data on a bus that is 64 data bits wide, and since a byte comprises 8 bits, this equates to 8 bytes of data per transfer.

With two transfers per cycle of a quadrupledclock signal,a 64-bitwide DDR3 module may achieve a transfer rate of up to 64 times the memoryclockspeed. With data being transferred 64 bits at a time per memory module, DDR3 SDRAM gives a transfer rate of (memory clock rate) × 4 (for bus clock multiplier) × 2 (for data rate) × 64 (number of bits transferred) / 8 (number of bits in a byte). Thus with a memory clock frequency of 100 MHz, DDR3 SDRAM gives a maximum transfer rate of 6400MB/s.

The data rate (inMT/s) is twice the I/O bus clock (inMHz) due to thedouble data rateof DDR memory. As explained above, the bandwidth in MB/s is the data rate multiplied by eight.

CL –CAS Latencyclock cycles,between sending a column address to the memory and the beginning of the data in response

tRCD – Clock cycles between row activate and reads/writes

tRP – Clock cycles between row precharge and activate

Fractional frequencies are normally rounded down, but rounding up to 667 is common because of the exact number being 6662⁄3and rounding to the nearest whole number. Some manufacturers also round to a certain precision or round up instead. For example, PC3-10666 memory could be listed as PC3-10600 or PC3-10700.[23]

Note:All items listed above are specified byJEDECas JESD79-3F.[11]: 157–165 All RAM data rates in-between or above these listed specifications are not standardized by JEDEC—often they are simply manufacturer optimizations using higher-tolerance or overvolted chips. Of these non-standard specifications, the highest speeds would reach up to DDR3-3200.[24]

Alternative naming:DDR3 modules are often incorrectly labeled with the prefix PC (instead of PC3), for marketing reasons, followed by the data-rate. Under this convention PC3-10600 is listed as PC1333.[25]

Serial presence detect

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DDR3 memory utilizesserial presence detect.[26]Serial presence detect (SPD) is a standardized way to automatically access information about acomputer memory module,using a serial interface. It is typically used during thepower-on self-testfor automatic configuration of memory modules.

Release 4

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Release 4 of the DDR3Serial Presence Detect(SPD) document (SPD4_01_02_11) adds support for Load Reduction DIMMs and also for 16b-SO-DIMMs and 32b-SO-DIMMs.

JEDEC Solid State Technology Association announced the publication of Release 4 of the DDR3 Serial Presence Detect (SPD) document on September 1, 2011.[27]

XMP extension

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Intel Corporation officially introduced the eXtreme Memory Profile (XMP) Specification on March 23, 2007, to enable enthusiast performance extensions to the traditional JEDECSPDspecifications for DDR3 SDRAM.[28]

Variants

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In addition to bandwidth designations (e.g. DDR3-800D), and capacity variants, modules can be one of the following:

  1. ECC memory,which has an extra data byte lane used for correcting minor errors and detecting major errors for better reliability. Modules with ECC are identified by an additionalECCorEin their designation. For example: "PC3-6400 ECC", or PC3-8500E.[29]
  2. Registered or buffered memory,which improves signal integrity (and hence potentially clock rates and physical slot capacity) by electrically buffering the signals with aregister,at a cost of an extra clock of increased latency. Those modules are identified by an additionalRin their designation, for example PC3-6400R.[30]
  3. Non-registered (a.k.a. "unbuffered") RAMmay beidentified by an additionalUin the designation.[30]
  4. Fully bufferedmodules, which are designated byForFBand do not have the same notch position as other classes. Fully buffered modules cannot be used with motherboards that are made for registered modules, and the different notch position physically prevents their insertion.
  5. Load reducedmodules, which are designated byLRand are similar to registered/buffered memory, in a way that LRDIMM modules buffer both control and data lines while retaining the parallel nature of all signals. As such, LRDIMM memory provides large overall maximum memory capacities, while addressing some of the performance and power consumption issues ofFBmemory induced by the required conversion between serial and parallel signal forms.

Both FBDIMM (fully buffered) and LRDIMM (load reduced) memory types are designed primarily to control the amount of electric current flowing to and from the memory chips at any given time. They are not compatible with registered/buffered memory, and motherboards that require them usually will not accept any other kind of memory.

DDR3L and DDR3U extensions

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TheDDR3L(DDR3 Low Voltage) standard is an addendum to the JESD79-3 DDR3 Memory Device Standard specifying low voltage devices.[31]The DDR3L standard is 1.35 V and has the labelPC3Lfor its modules. Examples include DDR3L‐800 (PC3L-6400), DDR3L‐1066 (PC3L-8500), DDR3L‐1333 (PC3L-10600), and DDR3L‐1600 (PC3L-12800). Memory specified to DDR3L and DDR3U specifications is compatible with the original DDR3 standard, and can run at either the lower voltage or at 1.50 V.[32]However, devices that require DDR3L explicitly, which operate at 1.35 V, such as systems using mobile versions of fourth-generation Intel Core processors, are not compatible with 1.50 V DDR3 memory.[33]DDR3L is different from and incompatible with theLPDDR3mobile memory standard.

TheDDR3U(DDR3 Ultra Low Voltage) standard is 1.25 V and has the labelPC3Ufor its modules.[34]

JEDEC Solid State Technology Association announced the publication of JEDEC DDR3L on July 26, 2010[35]and the DDR3U in October 2011.[36]

Feature summary

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Components

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  • Introduction of asynchronous RESET pin
  • Support of system-level flight-time compensation
  • On-DIMMmirror-friendly DRAM pinout
  • Introduction of CWL (CAS write latency) per clock bin
  • On-die I/O calibration engine
  • READ and WRITE calibration
  • Dynamic ODT (On-Die-Termination) feature allows different termination values for Reads and Writes

Modules

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  • Fly-by command/address/control bus with on-DIMM termination
  • High-precision calibration resistors
  • Arenotbackwards compatible—DDR3 modules do not fit into DDR2 sockets; forcing them can damage the DIMM and/or the motherboard[37]

Technological advantages over DDR2

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  • Higher bandwidth performance, up to 2133 MT/s standardized
  • Slightly improved latencies, as measured in nanoseconds
  • Higher performance at low power (longer battery life in laptops)
  • Enhanced low-power features

See also

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Notes

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  1. ^Prior to revision F, the standard stated that 1.975 V was the absolute maximum DC rating.[12]

References

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  1. ^Cutress, Ian (2014-02-11)."I'M Intelligent Memory to release 16GB Unregistered DDR3 Modules".anandtech.com.Retrieved2015-04-20.
  2. ^ab"Samsung Demonstrates World's First DDR 3 Memory Prototype".Phys.org.17 February 2005.Retrieved23 June2019.
  3. ^"Our Proud Heritage from 2000 to 2009".Samsung Semiconductor.Samsung.Retrieved25 June2019.
  4. ^abSobolev, Vyacheslav (2005-05-31)."JEDEC: Memory standards on the way".DigiTimes.com.Archived fromthe originalon April 13, 2013.Retrieved2011-04-28.JEDEC is already well along in the development of the DDR3 standard, and we have been working on it for about three years now.... Following historical models, you could reasonably expect the same three-year transition to a new technology that you have seen for the last several generations of standard memory
  5. ^"IDF:" DDR3 won't catch up with DDR2 during 2009 "".pcpro.co.uk. 19 August 2008. Archived fromthe originalon 2009-04-02.Retrieved2009-06-17.
  6. ^Bryan, Gardiner (April 17, 2007)."DDR3 Memory Won't Be Mainstream Until 2009".ExtremeTech.com.Archived fromthe originalon 2008-05-16.Retrieved2009-06-17.
  7. ^Salisbury, Andy (2009-01-20)."New 50nm Process Will Make DDR3 Faster and Cheaper This Year".Pcgamer.Retrieved2009-06-17.
  8. ^"JEDEC Announces Publication of DDR4 Standard – JEDEC".JEDEC.Retrieved12 October2014.
  9. ^Shilov, Anton (August 16, 2010)."Next-Generation DDR4 Memory to Reach 4.266GHz – Report".XbitLabs.com.Archived fromthe originalon December 19, 2010.Retrieved2011-01-03.
  10. ^McCloskey, Alan,Research: DDR FAQ,archived fromthe originalon 2007-11-12,retrieved2007-10-18
  11. ^abc"DDR3 SDRAM standard (revision F)".JEDEC. July 2012.Retrieved2015-07-05.
  12. ^"DDR3 SDRAM standard (revision E)"(PDF).JEDEC. July 2010.Retrieved2015-07-05.
  13. ^Chang, Jaci (2004)."Design Considerations for the DDR3 Memory Sub-System"(PDF).Jedex. p. 4. Archived fromthe original(PDF)on 2012-07-24.Retrieved2020-08-12.
  14. ^Soderstrom, Thomas (2007-06-05)."Pipe Dreams: Six P35-DDR3 Motherboards Compared".Tom's Hardware.
  15. ^Fink, Wesley (2007-07-20)."Super Talent & TEAM: DDR3-1600 Is Here!".AnandTech.
  16. ^DocMemory (2007-02-21)."Memory Module Picture 2007".Archived fromthe originalon 2017-06-06.Retrieved2022-01-05.
  17. ^"204-Pin DDR3 SDRAM unbuffered SODIMM design specification".JEDEC. May 2014.Retrieved2015-07-05.
  18. ^"How Intel Plans to Transition Between DDR3 and DDR4 for the Mainstream".techpowerup.com.Retrieved19 March2018.
  19. ^Shilov, Anton (2008-10-29)."Kingston Rolls Out Industry's First 2GHz Memory Modules for Intel Core i7 Platforms".Xbit Laboratories. Archived fromthe originalon 2008-11-01.Retrieved2008-11-02.
  20. ^"Dell Energy Smart Solution Advisor".Essa.us.dell.com. Archived fromthe originalon 2013-08-01.Retrieved2013-07-28.
  21. ^http://www.kingston.com/dataSheets/KVR16N11_8.pdf[bare URL PDF]
  22. ^Cycle time is the inverse of the I/O bus clock frequency; e.g., 1/(100 MHz) = 10 ns per clock cycle.
  23. ^Pc3 10600 vs. pc3 10666 What's the difference – New-System-Build,Tomshardware.com, 13 November 2009,retrieved2012-01-23
  24. ^Corsair to offer fastest ever 3,200MHz Venegeance Pro DDR3,bit-tech.net, 2013-06-06,retrieved2024-02-15
  25. ^Crucial Value CT2KIT51264BA1339 PC1333 4GB Memory RAM (DDR3, CL9) Retail,www.amazon.co.uk, 2016-05-10,retrieved2016-05-10
  26. ^"Understanding DDR3 Serial Presence Detect (SPD) Table".simmtester.com.Retrieved12 December2015.
  27. ^"JEDEC Announces Publication of Release 4 of the DDR3 Serial Presence Detect Specification".
  28. ^"Intel Extreme memory Profile (Intel XMP) DDR3 Technology"(PDF).Retrieved2009-05-29.
  29. ^Memory technology evolution: an overview of system memory technologies(PDF),Hewlett-Packard, p. 18, archived fromthe original(PDF)on 2011-07-24
  30. ^ab"What is LR-DIMM, LRDIMM Memory? (Load-Reduce DIMM)".simmtester.com.Archived fromthe originalon 2014-09-03.Retrieved2014-08-29.
  31. ^"Addendum No. 1 to JESD79-3 – 1.35 V DDR3L-800, DDR3L-1066, DDR3L-1333, DDR3L-1600, and DDR3L-1866".May 2013.Retrieved2019-09-08.
  32. ^"Addendum No. 1 to JESD79-3 – 1.35 V DDR3L-800, DDR3L-1066, DDR3L-1333, DDR3L-1600, and DDR3L-1866".May 2013.Retrieved2019-09-08.DDR3L VDD/VDDQ requirements – Power Supply: DDR3L operation = 1.283 V to 1.45 V; DDR3 operation = 1.425 V to 1.575 V.. Once initialized for DDR3L operation, DDR3 operation may only be used if the device is in reset while VDD and VDDQ are changed for DDR3 operation
  33. ^"What is DDR3L Memory?".Dell.com.Dell.2016-10-03.Retrieved2016-10-04.
  34. ^"Addendum No. 2 to JESD79-3, 1.25 V DDR3U-800, DDR3U-1066, DDR3U-1333, and DDR3U-1600".October 2011.Retrieved2019-09-08.
  35. ^"Specification Will Encourage Lower Power Consumption for Countless Consumer Electronics, Networking and Computer Products".
  36. ^"Addendum No. 2 to JESD79-3, 1.25 V DDR3U-800, DDR3U-1066, DDR3U-1333, and DDR3U-1600".
  37. ^"DDR3: Frequently Asked Questions"(PDF).Archived fromthe original(PDF)on 2009-12-29.Retrieved2009-08-18.
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