 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 turbocharging your PCI Express speed. Why did they sponsor that when their marketing so prominently features PCI Express Gen 4 you might ask? Because MSI don't give a f**k what PCIe Gen you buy as long as it's MSI. So LOL here we go. If you've never heard of our tech quickie channel and you're wondering what the s- I think this backplate actually took the brunt of it. Oh nice. If you've never heard of our tech quickie channel and you're wondering what the Sam Hill a 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 two 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 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'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 CSGO. 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 CSGO 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 5 and the Xbox series 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 2 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 4 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 standout 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 Luxcore renderer. Finally, Specviewperf 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 gonna 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 4 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 2 or 3 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 datasets. 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's 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 upgrade. 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 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, X570, B550 to satisfy your rise and fix. Oh, and of course, their Z490 boards are already wired for Gen 4 when Rocket Lake launches, so we're gonna 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.