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DDR5 Demystified - Feat. Samsung DDR5-4800: A Look at Ranks, DPCs, and Do Manufacturers Matter?

 


The hottest advancement in memory technology for desktop computers in recent years is undoubtedly the release of DDR5 memory and Intel's 12th Gen Core series of processors. Not only does DDR5 memory yield higher memory bandwidth for many different use cases, but DDR5 also offers a generational increase in memory capacity, allowing for higher capacity UDIMMs over time.

But, as always, the memory market is anything but homogenous. Even with just three actual DRAM manufacturers, DIMM vendors are offering DDR5 at a slew of clockspeeds, both official JEDEC speeds and X.M.P. profile memory that essentially comes overclocked out of the box. There are also notable differences in today's common DDR5 DIMM configurations, including single-sided UDIMMs (1Rx8), and dual-sided memory (2Rx8), as well as UDIMMs with different capacities.

In today's piece, we're looking at DDR5-4800 memory from Samsung, including 2 x 32 GB, 2 x 16 GB, and 4 x 16 GB, to measure the performance differences between single and dual rank memory, as well as any differences between running DDR5 in one DIMM Per Channel (DPC) or two. Finally, as we have DDR5-4800 DIMMs with DRAM from Micron and SK Hynix, too, we'll also be looking at these in our results, to see if there are any performance differences among the three memory manufacturers.

Scaling With DDR5 Memory: The Story So Far

In December 2021, we tested the performance scalability of DDR5 memory using G.Skill's Trident Z5 2 x 16 GB kit of DDR5-6000 CL36 memory at a range of different frequencies. Our findings showed that going from JEDEC settings of DDR4-4800 CL36 up to DDR4-6400 CL36 yielded a performance gain of 14% when using one of our most memory-sensitive benchmarks, WinRAR 5.90. The consensus here was that using faster memory did allow for an uplift in practically all of the scenarios we tested. Still, the caveat was that due to the high prices of faster kits, there currently isn't any kind of price/performance sweet spot beyond current DDR5-4800 JEDEC kits – the price premium for high-speed kits is currently greater than the performance benefits.

Samsung DDR5-4800B CL40 memory (2 x 32 GB) (2Rx8)

Today's Test: Ranks, DPCs, and Do Memory Manufacturers Matter?

Since that initial article was focused on memory frequencies and latencies, we wanted to take a look at the other elements of the equation for DDR5 performance. This includes DIMM ranks, the number of DIMMs in a single memory channel, and even the memory manufacturers themselves. We've seen what happens when we play with the first two variables, now what happens when we play with the rest?

Focusing on DDR5 DIMM configurations, the DDR5 memory modules currently available for consumers using Intel's 12th Gen Core series come in four different combinations. This includes single rank (1Rx8) and dual rank (2Rx8) DIMMs, which in turn typically come in kits of two or four, making for 1 DIMM Per Channel (1DPC) or 2 DIMMs Per Channel (2DPC) respectively. And, as we'll see in our testing, both ranks and DPCs do impact DDR5 performance, so there is much more to getting the most out of DDR5 memory than just frequency and latencies.

The fundamental questions we want to answer in this article are:

  1. Is there a difference in performance between 1Rx8 and 2Rx8 with DDR5 memory?

  2. Is there a difference in performance when using 1DPC versus 2DPC (2x32GB vs. 4x16GB)?

  3. Is there a difference in performance between memory from different manufacturers at identical timings?

To explore the performance differences in of DDR5 operating in different ranks and DPCs, Samsung has sent over a collection of their latest DDR5-4800B DIMMs in two different configurations/capacities: 16GB 1Rx8 DIMMs, and 32GB 2Rx8 DIMMs. As one of the Big Three DRAM manufacturers, Samsung has an enormous presence in the memory market, but this is actually the first time the company has ever sampled consumer-grade UDIMMs. So we're excited to see how their own in-house DIMMs do in this respect.

With Samsung's DIMMs in hand, we've been able to test between the two different configurations, to see if 1Rx8 versus 2Rx8 is better from a performance perspective. We're also able to measure the impact of moving from 1DPC to 2DPC, an always interesting matter as DDR memory signaling has become increasingly difficult with each generation.

Crucial (Micron) DDR5-4800B CL40 memory (2 x 32 GB) (2Rx8)

Finally, as we already have 32 GB (2Rx8) kits from SK Hynix and Micron, this has also allowed us to do a true apples-to-apples comparison among different DIMM kits at stock JEDEC speeds. With JEDEC timings all memory should be equal, so this is the perfect opportunity to test and confirm that notion. Plus the additional DIMMs give us a good control to compare the performance of the Samsung DIMMs to, to make sure there aren't any Samsung-specific oddities going on.

Ranks & DPCs: A Quick Refresher

Looking at the configurations of DDR5 UDIMMs, there are two main types, 1Rx8 and 2Rx8. The R in the 1Rx8 stands for rank, so 1Rx8 means it has one rank with eight memory chips per rank. 2Rx8, in turn, means there are two ranks of eight memory chips. In practice, with today's DDR5 DIMMs, 1Rx8 will be a single-sided DIMM, whereas 2Rx8 is always dual-sided. We should note that there is also quad rank (4Rx8) memory as well, but this is typically found in servers and not usually meant for consumer platforms (where it may not even be supported to begin with).

Because the number of chips per rank is fixed – and so is the density of the first-gen DDR5 dies available today – the capacity of today's DDR5 DIMMs is directly proportional to the number of ranks. 32GB DIMMs are exclusively 2Rx8, using a total of 16 16Gb dies, while 16GB DIMMs will drop down to 8 of those dies.

And, of course, on most motherboards it's possible to populate either one or two DIMMs per Channel (DPC). Adding a second DIMM to a channel allows for doubling the total memory capacity of a system – going up to 128GB with today's systems – but it also comes with a potential performance tradeoff. Driving multiple DIMMs in a single memory channel is harder on the memory controller than driving a lone DIMM, which means going beyond two DIMMs can be a tradeoff between capacity and performance, rather than a means of increasing both. Which makes for a particularly interesting question right now when trying to build a 64GB system: is it better to go with two 2Rx8 DIMMs, or four 1Rx8 DIMMs?

Samsung, SK Hynix, and Micron DDR5 Manufacturing: The Differences

We have dedicated many column inches to DDR5 memory over the last couple of years; each memory manufacturer has its own process used to produce its memory ICs. Each different memory manufacturer also has its own manufacturing process and design application to create its dies for the memory chips.

DDR5 Manufacturing Differences/Specifications

(Samsung, SK Hynix, Micron)

Manufacturer

Samsung

SK Hynix

Micron

Speed (MT/s)

DDR5-4800

DDR5-4800

DDR5-4800

Bandwidth

38.4 GB/s

38.4 GB/s

38.4 GB/s

Die Area

73.58 mm²

75.21 mm²

66.26 mm²

Die Capacity

16 Gb

16 Gb

16 Gb

Process Node

Samsung D1y

SK Hynix D1y

Micron D1z

All of the DDR5-4800B memory we are testing in this article is what I like to call the 'early adopter DDR5', which means it's the using first iteration of DDR5 memory from each of the vendors.

On the early release silicon for DDR5 DRAM, each of its packaged dies measures up slightly different as each manufacturer uses its process. On the Samsung UDIMMs, it uses its SD1y node, with the die package area measuring at 73.55 mm². In contrast, the SK Hynix memory ICs measure at 75.21 mm² and uses that company's D1y node, while the smallest of the three is the Micron, with a package size of 66.26 mm² and is made using Micron's D1z node.

Looking forward, each of the Big Three is planning to use the latest in Extreme Ultraviolet (EUV) lithography to produce bigger, higher density, and faster dies in the future, many of which are already in early production. This includes the Samsung 14 nm node with EUV lithography, which should allow the mass production of DDR5-7200 memory (and hopefully, a JEDEC standard to go with it). Though as we're also dealing with the first generation of DDR5 memory controllers, the speeds attainable on Intel's 12th Gen Core, for example, are limited. When further advancements can be made, this should allow for faster DDR5 memory to be used in on future PC platforms.

ADATA (SK Hynix) DDR5-4800B CL40 memory (2 x 32 GB) (2Rx8)

Test Bed and Setup

Given DDR5 is a premium product, we have opted to use a premium platform for our test bed. This includes Intel's highest performing Core Series processor, the Core i9-12900K, and paired it up with a premium motherboard from MSI, the MSI MPG Z690 Carbon Wi-Fi. For our testing, we've left the Intel Core i9-12900K at default settings as per the firmware, with no changes made to CPU core frequency, memory frequency, or memory latencies.

For our testing, we are using the following:

DDR5 Memory Test Setup (Alder Lake)

Processor

Intel Core i9-12900K, $589

125 W, 8+8 Cores, 24 Threads

3.2 GHz Base, 5.2 GHz P-Core Turbo

Motherboard

MSI Z690 Carbon Wi-Fi

Cooling

MSI Coreliquid 360mm AIO

Power Supply

Corsair HX850

Memory

Samsung DDR5-4800B CL40 (2 x 16 GB) - 1Rx8/1PDC

Samsung DDR5-4800B CL40 (4 x 16 GB) - 1Rx8/2DPC

Samsung DDR5-4800B CL40 (2 x 32 GB) - 2Rx8/1DPC

SK Hynix DDR5-4800B CL40 (2 x 32 GB) - 2Rx8/1DPC

Micron DDR5-4800B CL40 (2 x 32 GB) - 2Rx8/1DPC

Video Card

NVIDIA RTX 2080 Ti, Driver 496.49

Hard Drive

Crucial MX300 1TB

Case

Open Benchtable BC1.1 (Silver)

Operating System

Windows 11 Up to Date

Head on to the next page as we test the different DDR5-4800B memory kits and give our analysis.

CPU Performance Benchmarks: DDR5-4800

To show the performance of DDR5 memory in different configurations, we've opted for a more selective and short-form selection of benchmarks from our test suite. This ranges from tests on application opening, rendering, web, and compression.

All of the tests were run with all of the memory at default (JEDEC) settings, which means DDR5-4800 CL40, regardless of the configuration, e.g, 2x16, 2x32, and 4x16 GB.

Web: Speedometer 2

Our web test for this analysis is Speedometer 2, which is a test over a series of JavaScript frameworks to do three simple things: built a list, enable each item in the list, and remove the list. All the frameworks implement the same visual cues, but obviously apply them from different coding angles.

Our test goes through the list of frameworks, and produces a final score indicative of ‘rpm’, one of the benchmarks internal metrics.

We repeat over the benchmark for a dozen loops, taking the average of the last five.

Speedometer 2.0 Web Test

In Speedometer, the 2Rx8/1PDC DDR5-4800 kit performed best of all out of the Samsung memory, with the 1Rx8/1DPC performing closely behind the 2 x 32 GB kit. The 1Rx8/2PDC (4 x 16 GB) kit from Samsung technically performed the slowest of all, but the performance difference was within a 3% margin of error from top to bottom.

The Micron 2 x 32 GB proved the best out of all the memory we tested, albeit without much difference from the rest of the 2 x 32 GB kits tested.

AIDA64: 6.60: link

AIDA64 Extreme has a hardware detection engine unrivaled in its class. It provides detailed information about installed software and offers diagnostic functions and support for overclocking. As it is monitoring sensors in real-time, it can gather accurate voltage, temperature, and fan speed readings, while its diagnostic functions help detect and prevent hardware issues. It also offers a couple of benchmarks for measuring either the performance of individual hardware components or the whole system. It is compatible with all 32-bit and 64-bit Windows editions, including Windows 11 and Windows Server 2022.

We are using AIDA64 in this instance to gather memory bandwidth data based on read speed, write speed, copy speed, and memory latency.

AIDA DRAM Read Speed


AIDA DRAM Write Speed


AIDA DRAM Copy Speed


AIDA DRAM Latency

Looking at raw memory benchmarks from AIDA64, all of the 2 x 32 GB kits perform competitively against each other. Meanwhile the Samsung 4 x 16 GB experienced drops in performance across the board, with both read bandwidth and write bandwidth being impacted. There's also a notable latency penalty to consider when using four DIMMs (2DPC) versus two DIMMs (1DPC).

The most interesting result here may very well be the Samsung 2 x 16 GB (1Rx8) kit. While it's fully competitive with read speeds, it loses just a little bit of ground on write speeds, and a little more ground on all-out copies. In what's admittedly a memory-focused test, it's a very early indicator that dual ranked DIMMs are the sweet spot in terms of performance, and that losing a rank does incur penalties. All of which is then further exacerbated by going to 2DPC.

WinRAR 5.90: link

Our WinRAR test from 2013 is updated to the latest version of WinRAR at the start of 2014. We compress a set of 2867 files across 320 folders totaling 1.52 GB in size – 95% of these files are small typical website files, and the rest (90% of the size) are small 30-second 720p videos.

WinRAR 5.90 Test, 3477 files, 1.96 GB

Looking at performance in WinRAR, this is where the higher density 2Rx8 memory showed its dominance. The kits with 16 Gb chips in 2Rx8 outperformed the 16 Gb 1Rx8, with the 2 x 16 GB Samsung kit notably outperforming the same memory running with four UDIMMs in a 2DPC configuration.

Rendering - Blender 2.79b: 3D Creation Suite

A high-profile rendering tool, Blender is open-source allowing for massive amounts of configurability, and is used by a number of high-profile animation studios worldwide. The organization recently released a Blender benchmark package, a couple of weeks after we had narrowed our Blender test for our new suite, however their test can take over an hour. For our results, we run one of the sub-tests in that suite through the command line - a standard ‘bmw27’ scene in CPU only mode, and measure the time to complete the render.

Blender 2.83 Custom Render Test

Focusing on rendering, the difference between the 2 x 32 and 2 x 16 GB kit was marginal. The 4 x 16 GB Samsung kit was technically the worst performer out of the bunch, but for all practical purposes, all 5 kits may as well be tied.

Rendering - Cinebench R23: link

Maxon's real-world and cross-platform Cinebench test suite has been a staple in benchmarking and rendering performance for many years. Its latest installment is the R23 version, which is based on its latest 23 code which uses updated compilers. It acts as a real-world system benchmark that incorporates common tasks and rendering workloads as opposed to less diverse benchmarks which only take measurements based on certain CPU functions. Cinebench R23 can also measure both single-threaded and multi-threaded performance.

CineBench R23 Single Thread


CineBench R23 Multi-Thread

Using CIneBench 23, there wasn't much difference between the 2 x 32 GB kits in the single-threaded test. In the multi-threaded test, the Samsung 2 x 16 GB kit actually performed better than the 2 x 32 GB kits, underscoring how all of the kits are essentially tied in this workload.

Rendering – POV-Ray 3.7.1: Ray Tracing - link

The Persistence of Vision Ray Tracer, or POV-Ray, is a freeware package for as the name suggests, ray tracing. It is a pure renderer, rather than modeling software, but the latest beta version contains a handy benchmark for stressing all processing threads on a platform. We have been using this test in motherboard reviews to test memory stability at various CPU speeds to good effect – if it passes the test, the IMC in the CPU is stable for a given CPU speed. As a CPU test, it runs for approximately 1-2 minutes on high-end platforms.

POV-Ray 3.7.1

In our POV-Ray testing, the Micron kit performed slightly better than the rest, with Samsung's 2 x 32 GB kit coming a close second. Both variations tested with the 16 GB sticks were slightly behind its higher density counterparts. There was around a 0.36% hit in performance when using four 16 GB memory sticks versus using two.

Gaming Performance Benchmarks: DDR5-4800

To show the performance of DDR5 memory in different configurations, we've opted for a more selective and short-form selection of benchmarks from our test suite. This includes Civilization VI, Grand Theft Auto V, and Strange Brigade (DirectX 12).

All of the tests were run with all of the memory at default (JEDEC) settings, which means DDR5-4800 CL40, regardless of the configuration, e.g, 2x16, 2x32, and 4x16 GB.

Civilization 6

Originally penned by Sid Meier and his team, the Civilization series of turn-based strategy games are a cult classic, and many an excuse for an all-nighter trying to get Gandhi to declare war on you due to an integer underflow. Truth be told I never actually played the first version, but I have played every edition from the second to the sixth, including the fourth as voiced by the late Leonard Nimoy, and it is a game that is easy to pick up, but hard to master.

Benchmarking Civilization has always been somewhat of an oxymoron – for a turn based strategy game, the frame rate is not necessarily the important thing here and even in the right mood, something as low as 5 frames per second can be enough. With Civilization 6 however, Firaxis went hardcore on visual fidelity, trying to pull you into the game. As a result, Civilization can taxing on graphics and CPUs as we crank up the details, especially in DirectX 12.

Civilization VI - 1080p Max - Average FPS


Civilization VI - 1080p Max - 95th Percentile


Civilization VI - 4K Min - Average FPS


Civilization VI - 4K Min - 95th Percentile

Despite games traditionally being a GPU bottleneck instead of a CPU/memory bottleneck, in our Civ VI testing we do find some small but statistically meaningful differences in our results. The 2 x 32 GB kits were the best of the bunch, with the Samsung 2 x 16 GB kit running slightly slower. The Samsung 4 x 16 GB kit however performed a couple of frames per second slower than the rest, coming in a bit over 3% slower than the 2 x 32 GB Samsung kit.

Grand Theft Auto V

The highly anticipated iteration of the Grand Theft Auto franchise hit the shelves on April 14th 2015, with both AMD and NVIDIA to help optimize the title. At this point GTA V is super old, but still super useful as a benchmark – it is a complicated test with many features that modern titles today still struggle with. With rumors of a GTA 6 on the horizon, I hope Rockstar make that benchmark as easy to use as this one is.

GTA doesn’t provide graphical presets, but opens up the options to users and extends the boundaries by pushing even the hardest systems to the limit using Rockstar’s Advanced Game Engine under DirectX 11. Whether the user is flying high in the mountains with long draw distances or dealing with assorted trash in the city, when cranked up to maximum it creates stunning visuals but hard work for both the CPU and the GPU.

The in-game benchmark consists of five scenarios: four short panning shots with varying lighting and weather effects, and a fifth action sequence that lasts around 90 seconds. We use only the final part of the benchmark, which combines a flight scene in a jet followed by an inner city drive-by through several intersections followed by ramming a tanker that explodes, causing other cars to explode as well. This is a mix of distance rendering followed by a detailed near-rendering action sequence, and the title thankfully spits out frame time data. The benchmark can also be called from the command line, making it very easy to use.

Grand Theft Auto V - 1080p Max - Average FPS


Grand Theft Auto V - 1080p Max - 95th Percentile


Grand Theft Auto V - 4K Low - Average FPS


Grand Theft Auto V - 4K Low - 95th Percentile

Using Grand Theft Auto V's built-in benchmark at 1080p, all of the JEDEC DDR5-4800B kits performed competitively with each other – albeit with a higher degree of variability than usual due to the nature of the game. Still, in our 4K testing, we see that Samsung 4 x 16 GB kit once again brings up the rear, this time falling behind the 2 x 32 GB kit by 7%.

Strange Brigade (DX12)

Strange Brigade is based in 1903’s Egypt and follows a story which is very similar to that of the Mummy film franchise. This particular third-person shooter is developed by Rebellion Developments which is more widely known for games such as the Sniper Elite and Alien vs Predator series. The game follows the hunt for Seteki the Witch Queen who has arisen once again and the only ‘troop’ who can ultimately stop her. Gameplay is cooperative-centric with a wide variety of different levels and many puzzles which need solving by the British colonial Secret Service agents sent to put an end to her reign of barbaric and brutality.

The game supports both the DirectX 12 and Vulkan APIs and houses its own built-in benchmark which offers various options up for customization including textures, anti-aliasing, reflections, draw distance and even allows users to enable or disable motion blur, ambient occlusion and tessellation among others. AMD has boasted previously that Strange Brigade is part of its Vulkan API implementation offering scalability for AMD multi-graphics card configurations. For our testing, we use the DirectX 12 benchmark.

Strange Brigade DX12 - 1080p Ultra - Average FPS


Strange Brigade DX12 - 1080p Ultra - 95th Percentile


Strange Brigade DX12 - 4K Low - Average FPS


Strange Brigade DX12 - 4K Low - 95th Percentile

There wasn't much difference in our testing between the 2 x 32 GB kits in our Strange Brigade Direct X12 testing. At 4K, the Samsung 4 x 16 GB once again performed slightly slower than the rest, although Samsung's 2 x 16 GB configuration performed in-line with the 2 x 32 GB kits.

Conclusion

When selecting a memory kit for a new system, the market is littered with many choices ranging in speed, heatsink design, RGB or no RGB, and capacity. In terms of DDR5 memory, the only platform that can utilize this at the moment is Intel's 12th Gen Core series, with its premier offerings coming in conjunction with the Z690 chipset. This is likely to change later on this year if AMD's Zen 4 architecture launches, but right now, the DDR5 market and the Alder Lake market are one in the same.

For today's article, we focused at looking at the performance differences (or lack thereof) in DDR5 in different rank and DIMM per channel configurations. While these elements are smaller factors in DDR5 performance than frequency and clockspeed, as we have found, they do have a meaningful impact on memory subsystem performance – and thus an impact on overall system performance.

Samsung DDR5-4800B: 1Rx8 (1DPC/2DPC) versus 2Rx8 (1DPC)

In testing Samsung's 2 x 32 GB (2Rx8) kit directly against a 4 x 16 GB (1Rx8) kit, we got some interesting results running at JEDEC speeds with Intel's Core i9-12900K processor. 

WinRAR 5.90 Test, 3477 files, 1.96 GB

Looking at situations where the differences were evident in benchmark results, in our WinRAR 5.90 test, which is very sensitive to memory performance and throughput, the Samsung DDR5-4800 4 x 16 GB kit performed around 9% worse than its higher density 2 x 32 GB counterpart, which is quite a drop. And even in a 1DPC configuration, the 2 x 16 GB kit with its single rank of memory does operate at a deficit versus the dual rank kits. This indicates that using 1DPC yields better performance in memory-sensitive applications than 2DPC. Meanwhile, the Samsung DDR5-4800B 2 x 32 GB configuration performed within a solid margin of error against SK Hynix and Micron kits.

Grand Theft Auto V - 4K Low - Average FPS

It was much the same in some of our game testing, with the Samsung 4 x 16 GB kit being outperformed by the 2 x 32 GB kits, and even the Samsung 2 x 16 GB kit, which is the same single-rank UDIMMs as the 4 x 16 GB combination. While the performance hit was only around 2-3% in Grand Theft Auto V at 4K low settings, in our testing and from a performance point of view, Intel's Alder Lake seems to perform better with two sticks against four sticks of memory.

Throughout most of our testing, it was clear that in most situations, having two higher density 2Rx8 sticks in a 1DPC configuration versus the same capacity in 4 sticks (1Rx8 at 2DPC) is better for overall performance. And even looking at just 1DPC configurations, going dual-rank is still better, though to a smaller degree.

Going under the hood for an explaination for these results, the main reason that 2Rx8 is better than 1Rx8 comes down to how the integrated memory controller can only access one level of rank at a time. So in a dual rank DIMM, Rank Interleaving can be employed, which allows the second rank of memory chips to be ready for immediate access. While the differences are minimal even on a theoretical basis, as we have seen they are not zero: rank interleaving reduces response times in the pipeline refresh cycles, which can mean more performance in latency-sensitive applications, or when an application is going to be able to push DDR5 to its overall bandwidth limits.

Samsung vs SK Hynix vs Micron 32GB DDR5-4800B

Looking at the performance of the 2 x 32 GB kits running at DDR5-4800B from Samsung, SK Hynix, and Micron, the difference was for all practical purposes non-existent. We did not find any meaningful performance difference in our testing, which means that performance isn't a differentiating factor between the three memory manufacturers – at least at JEDEC settings with Alder Lake. Which, given the identical timings and capacities, is not unexpected. This is essentially the null hypothesis of our testing, showcasing that at least from a performance standpoint at fully qualified clockspeeds, there's no innate performance difference from one DRAM manufacturer to another.

Consequently, it's pretty easy here to recommend that if users are planning to build an Intel 12th Gen Core series setup with JEDEC-rated DD5 memory, they should opt for the cheapest option among proven DIMM vendors. For desktop purposes, the DIMMs are functionally equal, and right now DDR5 memory itself is still rather expensive. Although there's much more choice available in stock than there was last year, and it's still a relatively new platform, so that also adds to the cost.

Final Thoughts: 64GB of 2Rx8 with 1DPC is Better Than 64 GB of 1Rx8 with 2DPC

One of the biggest things to note from this article is that there isn't really any difference in performance between Samsung, SK Hynix, or Micron-based 2 x 32 GB DDR5-4800B memory kits. Despite using different memory ICs from each of the vendors, all these kits show that 2Rx8 DDR5 memory performs better than 1Rx8 DDR5.

The only aspect we didn't test was overclocking headroom with the JEDEC-rated kits, which wasn't really an angle we wanted base an article around. Given the lottery-like results of overclocking on any given DIMM, we'd be testing our own luck more than we'd be testing the hardware. In these cases a large sample size is required to get useful data, and that's where the dedicated memory vendors come in with their binning processes.

Taking a more meta overview on the state of the DDR5 market, we already know from vendors such as ADATA, G.Skill, and TeamGroup, that Samsung and SK Hynix's current generation parts show greater frequency and latency headroom when running above DDR5's nominal voltage of 1.1v. Which is why DDR5-6000 (and beyond) kits aren't using Micron chips. Though this may change in the future as all three companies are looking to the future with its manufacturing process, including EUV lithography.

2 x 32 GB kits of DDR5-4800B memory outperform 4 x 16 GB kits at the same frequency/latencies

As for the matter of today's tests, our results are very clear: dual-rank memory is the way to go, as is sticking to a single DIMM per channel when possible.

The most significant performance differences in our testing are found comparing two of Samsung's 1Rx8 DDR5-4800B memory sticks in a 1DPC configuration against four of the same sticks in a 2DPC configuration. There we find that the 1DPC configuration is contently equal or better in every scenario. Using four sticks means data has to travel further along the memory traces, which combined with the overhead of communicating with two DIMMs, results in both a drop in memory performance as well as a sight increase in latency.

And while the differences between 1Rx8 and 2Rx8 are not as large, we find that there is still a difference, and it's in favor of the dual rank memory. Thanks to rank interleaving, single rank memory finds itself at a slight disadvantage versus dual rank memory, at least on today's Alder Lake systems.

Based on this data, we recommend that users looking for 64 GB of DDR5 memory opt for 2 x 32 GB, rather than using a 4 x 16 GB configuration. Besides providing the best performance, the 2 x 32 GB route also leaves room for users to add additional capacity as needed down the line. Plus, if users want to overclock them further, overclocking four sticks of memory is notoriously stressful for the processor's IMC – and DDR5 only makes this worse.

Otherwise, choosing between DDR5-4800B kits from Micron, SK Hynix, and Samsung in terms of 2 x 32 GB kits primarily comes comes down to availability and price. DRAM is a true commodity product, in every sense of the word, so for these JEDEC-standard kits, there's not much to compete on except pricing.


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