DDR3 SDRAM
DDR3 SDRAM
DDR3 SDRAM
DDR3 SDRAM
DDR3 SDRAM[edit]Overview
DDR3memorypromisesapowerconsumptionreductionof30%comparedtocurrentcommercialDDR2modulesduetoDDR3's1.5Vsupplyvoltage,comparedtoDDR2's1.8VorDDR's2.5V.The1.5Vsupplyvoltageworkswellwiththe90nanometerfabricationtechnologyusedformostDDR3chips.Somemanufacturersfurtherproposeusing"dual-gate"transistorstoreduceleakageofcurrent.[1]
AccordingtoJEDEC[2]themaximumrecommendedvoltageis1.575voltsandshouldbeconsideredtheabsolutemaximumwhenmemorystabilityistheforemostconsideration,suchasinserversorothermissioncriticaldevices.Inaddition,JEDECstatesthatmemorymodulesmustwithstandupto1.975voltsbeforeincurringpermanentdamage,althoughtheyarenotrequiredtofunctioncorrectlyatthatlevel.
ThemainbenefitofDDR3comesfromthehigherbandwidthmadepossiblebyDDR3's8bitdeepprefetchbuffer,incontrasttoDDR2's4bitprefetchbufferorDDR's2bitbuffer.
DDR3modulescantransferdataattheeffectiveclockrateof800–1600MHzusingbothrisingandfallingedgesofa400–800MHzI/Oclock.Incomparison,DDR2'scurrentrangeofeffectivedatatransferrateis400–800MHzusinga200–400MHzI/Oclock,andDDR'srangeis200–400MHzbasedona100–200MHzI/Oclock.Todate,thegraphicscardmarkethasbeenthedriverofsuchbandwidthrequirements,wherehighbandwidthdatatransferbetweenframebuffersisrequired.
DDR3prototypeswereannouncedinearly2005.Productsintheformofmotherboardsareappearingonthemarketasofmid-2007[3]basedonIntel'sP35"bearlake"chipsetandmemoryDIMMsatbandwidthsuptoDDR3-1600(PC3-12800).[4]AMD'sroadmapindicatestheirownadoptionofDDR3in2008.
DDR3DIMMshave240pins,thesamenumberasDDR2,andarethesamesize,butareelectricallyincompatibleandhaveadifferentkeynotchlocation.[5]DDR3SO-DIMMshave204pins.[6]
[edit]Latencies
Thissectiondoesnotciteanyreferencesorsources.
Pleasehelpimprovethissectionbyaddingcitationstoreliablesources.Unverifiablematerialmaybechallengedandremoved.(May2008)
WhilethetypicallatenciesforajEDECDDR2devicewere5-5-5-15,thestandardlatenciesforthenewerJEDECDDR3devicesare7-7-7-20forDDR3-1066and7-7-7-24forDDR3-1333.Onethingtobeawareof,however,isthatwhilethesearethestandards,manufacturingprocessestendtoimprovewithtime.Eventually,DDR3moduleswilllikelybeabletorunatlowerlatenciesthantheJEDECspecifications.ItispossibletofindDDR2memorythathaslowerthanthestandard5-5-5-15timings,butitwilltaketimeforDDR3tofallbelowtheJEDEClatencies.
DDR3latenciesarenumericallyhigherbecausetheclockcyclesbywhichtheyaremeasuredareshorter;theactualtimeintervalisgenerallyequaltoorlowerthanDDR2latencies.
GDDR3memory,havingasimilarnamebutbeingfromanentirelydissimilartechnology,hasbeeninuseforhigh-endgraphiccardsbycompaniessuchasNVIDIAandATITechnologies.GDDR3hassometimesbeenincorrectlyreferredtoas"DDR3".
[edit]Extensions
IntelCorporationofficiallyintroducedtheeXtendedMemoryProfile(XMP)SpecificationonMarch23rd,2007toenableenthusiastperformanceextensionstothetraditionalJEDECSPDspecificationsforDDR3SDRAM.[7]
[edit]SpecificationStandards
[edit]Chipsandmodules
StandardnameMemoryclockCycletimeI/OBusclockDatatransferspersecondModulenamePeaktransferrate
DDR3-800100MHz10ns400MHz800MillionPC3-64006400MB/s
DDR3-1066133MHz7.5ns533MHz1066MillionPC3-85008533MB/s
DDR3-1333166MHz6ns667MHz1333MillionPC3-1060010667MB/s[1]
DDR3-1600200MHz5ns800MHz1600MillionPC3-1280012800MB/s
Features
DDR3SDRAMComponents:
IntroductionofasynchronousRESETpin
Supportofsystemlevelflighttimecompensation
On-DIMMmirrorfriendlyDRAMpinout
IntroductionofCWL(CASWriteLatency)perclockbin
On-dieI/Ocalibrationengine
READandWRITEcalibration
DDR3Modules:
Fly-bycommand/address/controlbuswithon-DIMMtermination
Highprecisioncalibrationresistors
Arenotbackwardscompatible-wronglyinsertingaDDR3moduleintoaDDR2socketcandamagetheDIMMand/orthemotherboard[2]
AdvantagescomparedtoDDR2
Higherbandwidthperformance,effectivelyupto1600MHz
Higherperformanceatlowpower(longerbatterylifeinlaptops)
Enhancedlowpowerfeatures
Improvedthermaldesign(cooler)
DisadvantagescomparedtoDDR2
CommonlyhigherCASlatency
Currently(asof2008)costsmuchmorethanequivalentDDR2memory
[edit]References
^McCloskey.,Alan."Research:DDRFAQ".Retrievedon2007-10-18.
^JEDECJESD79-3A(section6,tables21and22)
^Soderstrom,Thomas(2007-06-05)."PipeDreams:SixP35-DDR3MotherboardsCompared".Tom'sHardware.
^Fink,Wesley(2007-07-20)."SuperTalent&TEAM:DDR3-1600IsHere!".AnandTech.
^"DocMemory"(2007-02-21)."MemoryModulePicture2007".
^"JEDEC"(2008-01-01)."204-PinDDR3SDRAMSO-DIMMSpecification".
^Coles,Olin."DDR3RAM:SystemMemoryTechnologyExplained".Retrievedon2008-05-11.
[edit]Seealso
DDR2SDRAM
FullyBufferedDIMM
Dualchannel
Listofdevicebandwidths
[edit]Externallinks
Coles,Olin(2008-05-11)."DDR3RAM:SystemMemoryTechnologyExplained".BenchmarkReviews.
Gavrichenkov,Ilya(2007-07-09)."DDR3SDRAM:RevolutionorEvolution?".X-bitlabs.
Mahajan,Raj."MemoryDesignConsiderationsWhenMigratingtoDDR3InterfacesfromDDR2".MemCoreIncwww.memcoreinc.com.
Agostinelli,Gregory."MethodandApparatusforfinetuningamemoryinterface".USPATENTOFFICE.
JEDECDDR3-StandardJESD79-3
CompareDDRDDR2andDDR3articleatRMRoberts.comwebsite
Retrievedfrom"http://en.wikipedia.org/wiki/DDR3_SDRAM"
Categories:SDRAM
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