- Surely, a shiny new PCI express Gen 4 system
is gonna 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 gonna be digging deep
into the performance impact
of turbo charging your PCI Express speed.
Why did they sponsor that when they're marketing
so prominently features PCI express Gen 4 you might ask.
Cause MSI don't give a (beep) what PCIe Gen you buy
as long as it's MSI.
So LOL, here we go.
(upbeat music)
If you've never heard of our Techquickie channel
and you're wondering what...
(crashing)
I think this back plate 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 a PCI Express is,
the TLDR is it's the method
that modern CPU's 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 costs.
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 two gigabytes per second per lane.
That means that our featured card here
an MSI GeForce RTX 3090 Suprim X
can be fed at nearly 32 gigabytes per second
on a compliant motherboard, a 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 nine 5950X
and a top of the line, MSI X570 GODLIKE motherboard
to remove as many other system bottlenecks as possible.
We're also gonna throw an RX 6900 XT 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, 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 it 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 four, F1 2020
and Red Dead Redemption two,
where Gen 3 frame rates are consistently
a framer 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 four.
F1 2020 and Red Dead Redemption two 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%.
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 five
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 still ways off 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 KUDA mode
while optics is a complete wash
but then we quickly found an improvement in V-Ray.
Where we saw measurable bumps in both KUDA
and RTX enabled workflows.
DaVinci Resolve two, 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 LuxMark four,
though where we're looking at
a roughly 3% improvement
and OctaneBench doesn't meaningfully improve at all.
As for SPECviewperf 2020 most of this is so close
that we might as well call it a tie outside of Maya's
stand out 1% 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 11% in the Hall Bench.
That is definitely nothing to sneeze at
if you use LuxCoreRender.
Finally, SPECviewperf brings me back to
they are 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 gen four 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 5950 X today.
That is a significantly faster CPU
than the 3900 X that we used last time.
And the 3900 XT that GamersNexus used in their video.
So, could it be that Intel's upcoming Rocket Lake CPU's
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 it 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 chip set.
A faster link here means faster storage ports
faster network ports, more USB ports, et cetera, et cetera.
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.
Now, 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 MVME storage server.
We've got a gen four carrier card
that has eight gen three 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 X 570 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 we're V-Ray by about two or 3%
and Lux Mark 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 the Intel's bringing it
with their upcoming Rocket Lake CPU's
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 PCI-E
toss in some re-sizable BAR support, sprinkle on faster RAM
and a pinch of community optimizations.
And all of a sudden, you've got a pretty
compelling generational upgrade.
So, you know what I say, keep it coming.
Just like I keep the sponsors coming.
Big thanks to NSI for providing us all the equipment
and sponsoring this deep dive into PCI Express Gen 3
versus Gen 4 performance.
Go check them out.
We use their top end stuff here
but their gaming X trio cards are also great for performance
and they have a wide range of motherboards,
X 570, B 550 to satisfy your rise and fix.
Oh, and of course there's 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.