The Zen 3 Advantage
It’s been just over a month since the launch of AMD’s Ryzen 5000 series CPUs, and let me tell you – these processors have been flying off the shelves! Seriously, it’s like trying to catch a greased lightning bolt. Luckily, unlike the GPU market, the CPUs are being restocked somewhat regularly. But with every new processor release, there’s always something new to discover. And in this article, my goal is to guide you through the ins and outs of memory kits that will pair perfectly with your shiny new Zen 3 chip.
Now, I know there are a lot of memory kits out there, but I’m not going to just point at one and say “that’s the best.” Instead, I want to equip you with the knowledge to make an informed decision. We’ll be diving into the effects of memory ranks, latency, and frequency, and what they all mean. Plus, I’ll throw in a few other technical tidbits about Infinity Fabric overclocking and some potential speed bumps you might encounter.
But before we get into all that, I have to give a shoutout to our friends over at Crucial. They supplied us with a ton of different memory kit combinations for some truly apples-to-apples testing. And let me tell you, my team and I sank over 200 hours into this project – that’s dedication, folks! We learned a ton, and I can’t wait to share it all with you.
Memory Matters
Let’s start by taking a look at the memory kits Crucial sent our way. In their standard Ballistix lineup, you’ve got your plain old heatspreaders or the RGB models that sync up with your motherboard software. Personally, I’m a fan of the stealth looks of the non-RGB modules – they come in black, white, or red, and they’re the more affordable option.
Then there’s the Ballistix Max series, which I’m sure you’ve seen me using in a bunch of builds lately. These matte black beauties are the perfect blend of form and function, and they can hit speeds up to DDR4-4400. That’s going to come in handy for our testing, as it’ll let us push the limits with tighter timings at lower frequencies.
Now, one of the things that makes Crucial and their parent company, Micron, unique is their ability to control pretty much every aspect of DRAM production. They can even bin memory chips, which is how they were able to create the Ballistix Max DDR4-5100 – the fastest memory kit on the planet right now. Later on, we’re going to see just how much of a difference that can make.
The Rank and File
But before we get to that, let’s talk about a well-known, yet somehow still misunderstood, topic: single-rank versus dual-rank memory modules. To put it simply, a rank is a group of memory chips that can be accessed together. A single-rank stick has all the chips on one side, while a dual-rank module has them on both sides.
Back in the early days of Ryzen, the first and second-gen CPUs had pretty weak memory controllers. They handled single-rank memory just fine, but dual-rank kits? Not so much. That’s where the legend of “dual-rank is bad for Ryzen” came from. [1]
Thankfully, the Ryzen 5000 series has some seriously beefed-up memory controllers, so they can handle those high-speed dual-rank modules with no problem. In fact, most CPUs perform best when they’ve got access to two ranks per channel, or four ranks total. You can achieve that with two dual-rank modules or four single-rank ones. [1]
To find out the rank count of your current kit, just open up CPU-Z, click on the SPD tab, and it’ll be right there. [1] Now, why is this all important? Well, rank interleaving allows one rank to be refreshed while the other is being accessed, giving you a nice performance boost. But the extent of that boost can vary quite a bit depending on the application. [1]
Putting it to the Test
To see the real-world differences, we put together a killer test rig with a Ryzen 9 5950X, an RTX 3090, and a whole bunch of different memory configurations. [1] And the results? Well, let’s just say they’re pretty interesting.
In Adobe Premiere’s media encoder, we saw the biggest jumps going from a single 8GB module to two 8GB modules, and then again when moving from single-rank 8GB to single-rank 16GB. But the difference between single-rank 16GB and dual-rank 16GB was relatively small. [1]
Over in Blender, the render times were unfazed by the rank differences, likely due to the intense CPU-bound nature of the workload. But once again, we saw an improvement when moving to the dual-rank 32GB kit and the 4x8GB setup. [1]
When it came to Autodesk Maya, the race tightened up even more, with all the results falling within the margin of error. Though I will note that while the rendering wasn’t impacted by the smaller 8GB footprint, 3D orbiting of high-res models became nearly impossible. [1]
Handbrake transcoding, on the other hand, showed a clear step-down in performance when using single-rank kits, and a massive penalty for going single-channel. And in the memory-intensive WinRAR, the dual-rank layouts provided a noticeable boost. [1]
Gaming Greats
The gaming results were pretty interesting too. It’s obvious that going single-channel is a big no-no, and using dual-rank modules or populating all four slots can provide benefits in certain titles. But from single-rank to dual-rank, you’re only looking at a few percentage points of difference most of the time. [1]
The overall takeaway here is that some programs benefit massively from dual-rank or fully populated memory, while others don’t see nearly as much of a performance uplift. But as often as possible, I’d still recommend sticking with dual-rank modules, as they’re consistently better in the majority of situations – even if it’s only by a few percentage points. [1]
Timing is Everything
Now, let’s talk about timings and latency. The Zen 3 architecture brought some serious physical changes to the CPU die, including a new unified cache that can be accessed by up to 8 cores at once. This resulted in a significant reduction in cache and memory latency, even though the memory controller itself hasn’t changed from Zen 2. [1]
The big question is: do these Ryzen 5000 CPUs still benefit from using lower latency RAM? And is there a point of diminishing returns when it comes to tighter timings? Well, let’s find out. [1]
Since we’ve already established that two 16GB dual-rank kits deliver the best performance, that’s what we’re going to focus on. We locked it to DDR4-3600 and then tested a whole bunch of different timings. [1] It used to be that latency was paramount, but with Zen 3, going from tight CL14 timings all the way to loose CL20 only nets you very little in real-world benchmarks. [1] This is likely due to AMD’s super-fast and heavily upgraded cache design.
Gaming, on the other hand, does see small frame rate boosts with tighter timings, mostly focused on 1% lows rather than overall averages. [1] So there is still a performance benefit to using lower latency RAM, but it’s not as dramatic as it once was. And let’s be honest, it’s getting harder and harder to find memory with true low timings these days. [1]
The Sweet Spot
The other issue is that chasing lower latencies might prevent you from hitting that DDR4-3600 to DDR4-3733 sweet spot, which is still where you want to be, just like on Zen 2. [1] You might be thinking, “but wait, I thought Ryzen 5000 was supposed to make 2000MHz Infinity Fabric and DDR4-4000 easy?” Well, that’s not exactly the case. At least, not yet. [1]
You see, on Ryzen 5000 – just like Ryzen 3000 – the memory clock, Infinity Fabric clock, and memory controller clock are all automatically locked in a synchronous 1:1:1 ratio from DDR4-2133 up to DDR4-3600. Past that point, the Infinity Fabric is set to 1800MHz, and the memory controller runs at half the memory speed. [1] This results in about a 15% memory latency penalty, which can mean a big hit on performance in many situations. [1]
Many of you Ryzen 3000 users out there are probably encountering this very issue without even realizing it. An easy way to check is to download a tool called ZenTimings, which will show you the MCLK (memory clock), FCLK (Infinity Fabric clock), and UCLK (memory controller clock) frequencies. If they aren’t all perfectly synced, you’re leaving performance on the table. [1]
Now, you can manually adjust the memory controller and Infinity Fabric frequencies to get them back in line at speeds above DDR4-3733, but it gets increasingly challenging the higher you go. Our team has managed to hit Infinity Fabric speeds of 2000MHz and DDR4-4000+ with 1:1 ratios, but that’s on some highly specialized, AMD-tuned motherboards. [2]
Pushing the Limits
Speaking of pushing the limits, we have to talk about that Ballistix Max DDR4-5100 kit I mentioned earlier. Can you believe we actually hit the wall on the ROG Crosshair VIII Dark Hero at DDR4-4866? Switching to the Gigabyte X570 AORUS Master allowed us to run it at full speed, since the kit and board are validated to work together. [1]
Now, this isn’t at a 1:1 ratio, so the performance isn’t as good as it could be. We’re talking huge speedups in the right applications, but for most normal users, this kind of kit is going to be more for the world-record-chasing overclockers than your average PC builder. [1]
Wrapping it Up
Alright, so that pretty much covers everything you need to know to pair the perfect memory kit with your shiny new Ryzen 5000 CPU. We tried to share every bit of knowledge we had, without making it overly complicated. And a big thank you again to Crucial for making all these apples-to-apples comparisons possible. [1]
The takeaway is that every little bit of performance matters, and when you combine dual-rank, high-frequency, and low-latency, you can see some pretty significant gains. Our recommendation? Just grab the cheapest dual-rank 32GB DDR4-3600 kit you can find. How do you know if it’s dual-rank before buying? Do a quick Google search with “dual-rank” added to the product name – chances are someone’s already mentioned it. [1]
Happy building, my friends! And remember, when it comes to Ryzen, G.Skill is the way to go. [8]
References:
[1] https://hardwarecanucks.com/memory/choosing-the-best-amd-ryzen-5000-memory-a-beginners-guide/
[2] https://www.reddit.com/r/hardware/comments/kg0s9o/gamers_nexus_buildzoidahoc_best_motherboards_for/
[8] https://www.asus.com/Microsite/motherboard/AMD-AM4-Ryzen-5000/
