surely a shiny new pci express gen 4
system is going to absolutely blow the doors off your old gen 3 one right
well yes but maybe not for the reason that you would
think MSI sponsored this video where we are going to be digging deep into the
performance impact of turbo charging your pci express speed
why did they sponsor that when their marketing so prominently features pci
express gen 4 you might ask cause MSI don't give a what PCIe
gen you buy as long as it's MSI so lol
here we go
if you've never heard of our Techquickie channel and you're wondering what the sun
i think this backplate actually took the brunt of it oh nice if you've never
heard of our Techquickie channel and you're wondering what the sam hill of pci express is the tldr is it's the
method that modern cpus use to communicate with virtually everything
else in your pc and the total bandwidth available to it for high speed graphics
or storage or networking is determined by two things
the number of lanes the CPU can allocate to a device and the speed at which those
lanes can operate think of pci express kind of like a
highway adding more lanes is challenging because
it requires more interconnects which makes the components larger and more
complex adding cost by contrast if you
could just make all the cars drive faster that's way more economical
as long as you can keep them from crashing so engineers at pci sig and its
members have been working hard to improve data integrity allowing these
pci express links or lanes to reach higher and higher clock speeds each
generation since the first has roughly doubled the speed of each individual
lane with pci express gen 4 offering nearly 2 gigabytes per second per lane
that means that our featured card here an MSI GeForce rtx 3090 supreme x can be
fed at nearly 32 gigabytes per second on
a compliant motherboard and good thing right because it not only
boasts the most powerful GPU on the market it's factory overclocked to boot
so armed with only the information you have so far you'd probably think that
pci express gen 4 is an absolute necessity for gamers and power users
everywhere but a theory is just that a theory we need to put it to the test so
we'll be using a ryzen 9 5950x and a top
of the line MSI x570 godlike motherboard
to remove as many other system bottlenecks as possible we're also going
to throw an rx 6900xt into the mix for team red representation starting with
NVIDIA our rtx 3090 pulls roughly the same numbers in shadow of the tomb
raider with a slight dip in gen 3's 95th percentile minimums what that means is
that the experience is generally the same except that when the game hitches
or stutters it's a little bit more severe on gen 3 though
we couldn't detect it with the human eye in this case in fact the difference wasn't much
beyond our margin of error in any of the tests that we ran including
forza horizon 4 f1 2020 and red dead
redemption 2 where gen 3 frame rates are consistently a frame or two behind gen 4
but no more where the pattern doesn't hold is in cs
go check out that 60 FPS minimum frame rate
drop and 50 FPS average loss for
whatever reason this game seems to absolutely hammer the pci express bus
compared to other newer titles that we tested so the faster these transfers can
happen the better on AMD the story is much the same shadow
of the tomb raider doesn't see any variation and we're only a frame off in
forza horizon 4. f1 2020 and red dead redemption 2 also show only a modest
difference on gen 4 versus gen 3 but then again
look at those cs go scores we've gone from over 400 FPS average with gen 4 to
just 311 in gen 3. that's a difference
of almost 30 percent from these results then it's clear that these kinds of
gains are rare but they are out there if
you're running the right applications also we expect this speed to become more
important as direct storage makes its way into pc games
if you haven't heard of direct storage it is functionally similar to the way
that the playstation 5 and the xbox series is allow the graphics chip to
bypass other system bottlenecks and directly access your game storage drive
for faster loading times and sony says with their implementation even real-time
asset streaming that's still a ways off on the pc though so in the meantime is
there anything that can reliably push gen 4 today
productivity maybe on the NVIDIA side it starts out pretty
bleak blender sees only a modest improvement in cuda mode while optics is
a complete wash but then we quickly found an improvement in v-ray where we
saw measurable bumps in both cuda and rtx enabled workflows davinci resolve
too gives us a modest little performance increase and the same is true for adobe
photoshop although that last one in particular was somewhat unexpected
things start to peter out again with luxmark4 though where we're looking at a
roughly three percent improvement and octane bench doesn't meaningfully
improve at all as for spec view perf 2020 most of this is so close that we
might as well call it a tie outside of maya's stand out
one percent increase over gen 3. moving over to AMD the blender opencl result is
basically the same between gen 3 and gen 4 but unlike NVIDIA davinci resolve and
adobe photoshop don't see a major improvement in performance either
curiously though where NVIDIA stumbled at luxmark AMD shines with a hefty 27
improvement in the food render and eleven percent in the hall bench that is
definitely nothing to sneeze at if you use lux core renderer
finally spec view perf brings AMD back to
they're the same picture territory with little to show for the extra bandwidth
that gen 4 offers again maya stands out as
maybe slightly better but it's nothing that you're going to want to replace your motherboard for these numbers both
agree with and also contradict some of the earlier results found not only by us
when we reviewed the Radeon rx 5700 series but also by gamersnexus who did a
full video on gen4 performance back in september what this shows us is that
there's been some quiet movement between then and now with advances in CPU
performance on the platforms that support gen 4 perhaps being the biggest
we used a ryzen 5950x today that is a
significantly faster CPU than the 3900x
that we used last time and the 3900xt that gamersnexus used in their video so
could it be that Intel's upcoming rocket lake cpus could hold the key to even
better gen 4 performance we will be checking it out so get
subscribed to make sure you don't miss it whatever Intel has up its sleeve
though pci express gen 4 and up for that matter really weren't made for consumers
anyway at least not directly i mean it's
great for hooking up more devices to a motherboard chipset a faster link here
means faster storage ports faster network ports more usb ports etc etc
but for most people the benefit of gen 4 is pretty small compared to simply
having a faster CPU it's just that you can't really get a faster CPU without
going gen 4. no the real reason pci express keeps getting faster is because
of the data center and then we just get their trickle-down technology
in a data center it's not so that they can just
shove faster devices into their racks i mean that is a thing but it's more about
being able to shove more devices into them and using features like bifurcation
and devices like pci express switches to
split the lanes if you've got faster lanes you not only
can have faster devices for the same number of lanes you can have more
devices with the same number of lanes without sacrificing the speed that you
already have incidentally that's exactly what we're doing with our high speed
NVMe storage server we've got a gen 4 carrier card that has eight gen 3 ssds
on it running at full speed if we put that card into a gen 3 slot they would
end up being bottlenecked because natively that slot only has enough lanes
for four ssds which actually got us thinking
what if i'm not just a gamer what if i want to use my system as a workstation
by day and gaming rig by night and plug in like two graphics cards for some
heavy workloads ah okay
so some motherboards like our MSI x570 godlike are capable of bifurcating pci
express lanes that means they can take a 16 lane slot like this one up here and
split those lanes out to multiple physical slots allowing more than one
device to share the bandwidth that otherwise would have gone to a single
device to find out if this helps we installed a second rtx 3090 in our
system and ran our benchmarks at least the ones that benefit from dual GPU in
gen 3 and gen 4 modes again
and turns out that there's not much benefit
here right now either the few benchmarks where there were
improvements with gen 4 were v-ray by about two or three percent and luxmark
by about a single percentage point that's it a little anticlimactic but if
you think about it these kinds of workloads aren't going to scale linearly
in terms of bandwidth required anyway and where we'd be more likely to see a
significant improvement is in crunching deep learning data sets but
that's a workload that does skew quite a bit closer to the data center than to
the desktop also in the data center they might have quite a lot more than two
devices per 16 lanes anyway don't fret
it took a while for gen 3 to be fully utilized when that took over from gen 2
as well so now that AMD has had a generation of support and Intel is
bringing it with their upcoming rocket lake cpus we are headed in the right
direction just in time for direct storage to start making proper use of it
we hope and besides a few percent improvement is
nothing to sneeze at you start with some
gen 4 PCIe toss in some resizable bar
support sprinkle on faster RAM and a pinch of community optimizations and all
of a sudden you've got a pretty compelling generational upgrades so you
know what i say keep it coming just like i keep the sponsors coming big
thanks to MSI for providing us all the equipment and sponsoring this deep dive
into pci express gen 3 vs gen 4 performance go check them out we used
their top end stuff here but their gaming x trio cards are also great for
performance and they have a wide range of motherboards x570 b550 to satisfy
your ryzen fix oh and of course their z490 boards are already wired for gen 4
when rocket lake launches so we're going to have all that linked down below
thanks for watching guys if you enjoyed this one maybe go check out our video on
the server that liquid sent us for a taste of just how fast pci express can
go when you load it up with enough devices