PCI-E
Peripheralcomponentinterconnectexpress,
orPCI-E,is thebackboneofanymodernPC,
withthissystembususedtocarryinformation
toandfromyourgraphicscard,storage
drives,Wi-Ficards,Ethernetandjustabout
anyotherdeviceinyoursystemasidefrom
memory.DesignedtoreplacetheolderPCI
andAGPinterfaces,youmaybesurprisedto
learnthat,despiteit carryinghugeamounts
ofinformationaroundyoursystem,and
beingbasedonmotherboard-tracedatalines
ina similarwaytoRAM,it is infacta serial
communicationsystem.
AllthattalkofPCI-Elanesyousee
whenreferringtographicscards,SSDs
andmotherboardchipsetsis referringto
multipleserialcommunicationlines.Each
laneconsistsofa pairoflines(eachofwhich
is actuallya pairofLVDSlines),withoneeach
fortransmittingandre ceiving.A graphics
cardthenusesupto 16 oftheselanesatthe
sametime,whileM.2SSDscanuseupto
fourlanesandotherslowercomponentswill
usejustone.
Forconnectionswithmultiplelanes,data
transmissionis spreadoutacrossthelanes
(striped)ina similarwaytoa RAID0 hard
driveconfiguration.Thismaintainsthespeed
advantagesofdataparallelism,butthe
parallelisationis happeningata higherlevel
inthesystem.
Oneoftheadvantagesofoperatingin
thiswayis thatthisserialsetupmakesfora
smallernumberofI/OpinsthanPCIanda
smallerphysicalfootprint,whichintheory
canresultincheapermotherboards.It also
makesthesystemscalable,withdifferent
motherboardchipsetsabletosupport
differentnumbersoflaneswithoutaffecting
anyoftheotherphysicalcomponentsofthe
system.A graphicscardslotorM.2slotwill
stillworkregardlessofwhetherthesystem
supportseightlanesor32.Therecanstillbea performancedifference
betweensystemsthatsupportdifferent
numbersoflanes– mostfamously,HEDT
motherboardchipsetsthatsupportmany
lanesaretheoreticallybetterforrunning
multiplegraphicscards– butit doesn’tmatter
asfarascompatibilityis concerned.
PCI-E4 hasbeeninthetechnewsa
lotrecently,withit firstarrivinginAMD’s
X570chipsetandcontroversiallynotbeing
supportedbyIntel’snewCometLake
processors.Regardless,theadvantages
ofthenewstandard,whichtechnicallyhas
twicethebandwidthofPCI-E3,appearsto
beminimalformostdevicesotherthanhigh-
speedSSDs.If graphicscardsdidn’temploy
theirownVRAMandconstantlyhadtobefed
dataoverthePCI-Ebus,it wouldbea very
differentstory,butrightnow,PCI-E3 appears
tobelargelyadequateforgraphicscards.''5 86(6 $ ˎ%,7 0(025<
INTERFACE WITH A WHOPPING
ˎ3,1 3+<6,&$/ &211(&7,21
TO THE MOTHERBOARD
SATA ports were a huge improvement over PATA
ports and their bulky cablesMost M.2 slots on new motherboards allow modern
SSDs to plumb directly into the PCI-E interface