D
espitebeingthesurprisememberofAMD’s 2017
Zenparty,andnotevena partofAMD’soriginal
plansforitsdesktopCPUonslaught,Threadripper
hasundergonethemostdramaticchangesofanyZen-
basedCPU.Wefirsthada modelwitheight, 12 and 16 cores.
Thenthe2nd-genchipsmaintainedcompatibilitywith
SocketTR4andtheX399chipset,whileadding 24 and
32-coremodels.
Thistime,AMDhasditchedanychipswithfewerthan
24 cores,withjusttwomodels sittinginthecurrentline-
up– onewith 24 coresandonewith 32 cores.However,
justbeforewewenttopress,AMDtoldusthata 64-core
Threadripperiswaitinginthewingstoo.Thedecisionto
keepThreadripperat 24
cores and above is likely
down to the Ryzen 9
3950X giving any chip
with fewer than 20 cores
a run a for its money
from both AMD and Intel –
it’s certainly more than
a match for last year’s
Threadripper 2950X.
A lot has changed
since last year, then, and
not only are core counts
on the rise yet again, but
under the hood, the new
3rd-gen Threadripper
CPUs are very different
from their predecessors
too. For starters, unlike
their 3rd-gen Ryzen
counterparts, which willSOCKETTRX4PROCESSORS
and 397
motherboards.Likew ,
workinthenewThreadrippermo
newTRX40chipset.FarewelltoTR
Whilethenewsocket’spincount remains the same as TR4,
thepinoutshavechangedsignificantly to accommodate
greaterscaling,namelythataforementioned 64-core
model.DespiteSocketTR4no longer having an upgrade
path,thenewSocketTRX4isotherwise physically identical
toitspredecessor.
Ontheplusside,thismeans that older TR4 coolers are
compatible with the new boards, which is at least some good
news if you’ve already invested in a Threadripper setup. If
you’re still using a 1st-gen Threadripper CPU and don’t want
to shell out for a whole new setup, AMD will also continue
selling 2nd-gen Threadripper CPUs alongside their Zen 2
counterparts, so there’s still some upgrade potential.Under the hood
The most profound changes to Threadripper, though, lie
under the heatspreader. The previous WX-series CPUs had
four dies with eight cores apiece, with some cores disabled
on the Threadripper 2970WX to account for its 24 cores as
opposed to 32. However, unlike their EPYC counterparts, the
WX-series dies weren’t created equal. Only two of the four
dies had direct access to the PCI-E bus, with the remaining
two dies having to go through the other dies to access it,
creating latency.
The same was true for the memory channels. Only one die
in each pair had access to channels A and B, with the other
die in each pair having sole access to the other two channels.rkinX370andX370boards,theThreadripper 396
7 notbackwardscompatiblewitholderTR
derThreadripperCPUswon’t
oardsbasedontheAll four CCDs can
now access all four
memory channels,
and access
the PCI-E bus
independently
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