DDR5 memory first hit the market in 2021 with the Intel LGA1700 platform and Alder Lake processors. As is usually the case with new technologies, users initially met it with great distrust. The reasons for this are well understood: at first, DDR5 modules were significantly more expensive than the ubiquitous DDR4, and high latencies negatively affected performance. But, having implemented DDR5 support, Intel prudently left DDR4 compatibility in the LGA1700 platform, which was actively used in systems in late 2021 – early 2022.
However, over time, the situation began to change. DDR5 prices gradually decreased, and the increased bandwidth increasingly compensated for the initial high latencies of the new memory, because the new standard was originally designed with an eye to working at significantly higher frequencies. And already in the second half of 2022, AMD came to the adoption of DDR5, implementing its support in the Socket AM5 platform, and on an uncontested basis, without the possibility of rolling back to DDR4. This became a kind of signal: the DDR4 era came to an end, and DDR5, on the contrary, began a phase of active development. High frequency, reduced power consumption and the ability to create larger modules did their job – users quickly accepted DDR5 as the main type of RAM for modern high-performance systems.
Another confirmation of the generational change that has taken place was the release of the LGA1851 platform in the second half of 2024, which completely lacks DDR4 support. As a result, both processor manufacturers have made a clear bet on DDR5, cutting off any “escape routes” for users. But Intel went even further: within the framework of the LGA1851 platform, which, according to the specification, is designed to work with DDR5-5600 and DDR5-6400, the company began to promote overclocker modules with a significantly increased frequency and increased bandwidth. Although LGA1700 processors also successfully coped with DDR5-7600 and even DDR5-8000 modules (with proper configuration and suitable hardware), the next step was taken with the release of Arrow Lake: they added support for a new type of DDR5 memory modules – CUDIMM, standardized by JEDEC at the beginning of last year. And that’s good news for all high performance enthusiasts.
The thing is that the main feature of CUDIMM is the presence of its own clock generator. Traditionally, in desktop systems, this signal is generated by the processor, but at high frequencies on the way to the memory, it can be subject to distortion due to interference and interference, which leads to failures and limits the overclocking potential of DDR5 modules. CUDIMM solves this problem by ensuring the stability of the reference signal directly on the module and, as a result, increasing the stability of DDR5 when operating at frequencies that were considered extreme until recently.
In this article, we will analyze how CUDIMM technology works and evaluate its real advantages and possible disadvantages. And as a visual aid in this analysis, a set of modules G.Skill Trident Z5 CK 48GB DDR5-8200 will be used.
⇡#How CUDIMMs differ from regular DDR5 modules
So, CUDIMM modules (which stands for Clocked Unbuffered Dual In-line Memory Modules) are designed to operate at high frequencies. While the speed limit of regular DDR5 SDRAM is around 8000 MHz, CUDIMM modules promise to raise the upper frequency limit by at least 25%. Support for such memory is very useful for Arrow Lake processors – they suffered greatly from the distribution of computing cores and memory controllers across different semiconductor crystals, and overclocking DDR5 can at least partially compensate for increased internal delays.
It is also important that the CUDIMM standard is based on the architecture of standard unbuffered DDR5 modules, which means that CUDIMMs are logically and hardware compatible with regular UDIMMs. In other words, CUDIMMs are inserted into the usual 288-pin DDR5 DIMM slots and can operate in compatibility mode even on platforms where support for such modules was not initially provided. However, the high frequencies of CUDIMM modules, for which they were invented, are achievable only on the LGA1851 platform, where their support is fully implemented.
The main secret of CUDIMM, which determines their special properties, is their own clock generator chip CKD (Clock Driver), which has never been previously found in conventional memory modules. Its task is to regenerate the reference clock signal coming to the memory chips installed on the module. Due to the fact that the frequency generator in CUDIMM buffers and distributes the clock signal to the memory chips directly on the module, each chip receives the same and accurate clocking without any distortions.
That is, it actually acts as an intermediate link, correcting the clock frequency signals coming from the processor, which are subject to attenuation and distortion during transmission along the contact lines of the motherboard. Both the time and amplitude components of these signals are restored, and this, in turn, eliminates potential problems with synchronization of memory chips and the controller in the processor. All this is especially important for high-frequency DDR5, when using which the probability of interference and desynchronization, leading to failures in the operation of the processor with memory, increases many times over.
Thus, in CUDIMM, the quality of the reference signal ceases to be a bottleneck for stable operation of memory modules at a high frequency. However, it should be understood that CUDIMM is not a registered module (similar to those used in servers), and signals on the command and address bus are not buffered in it. In this case, we are talking about eliminating only the first and most obvious problem, and in this sense, an additional clock generator in the module is not a panacea. A corrected reference signal allows increasing the frequency of stable DDR5 operation only until the moment when interference does not cause irreparable distortions of signals transmitted on the command and address bus, and this is why CUDIMM will not be able to move away from regular DDR5 modules in frequency as far as DDR5 modules have moved away from DDR4 SDRAM.
Depending on the application conditions, the CUDIMM frequency generator can operate in two modes: Single PLL and Dual PLL. The first option, used by default, assumes that the clock signal is regenerated for the entire module at once, i.e. all chips installed on the module receive the same reference signal. The second option, Dual PLL, assumes separate clocking of two 32-bit subchannels of the DDR5 module, and in this case the reference frequency is regenerated by the clock generator for each of them independently. It is assumed that the Dual PLL mode allows for better memory stability at ultra-high frequencies.
In addition, for the purposes of CUDIMM compatibility with systems that are not familiar with such modules, the clock generator has an additional Bypass mode. It is enabled if the CUDIMM module fails to initialize in Single PLL mode. In this case, the clock generator in the module is deactivated, and CUDIMMs turn into regular unbuffered DDR5 strips. Naturally, in this case, the stable operating frequencies of CUDIMMs will be lower than those stipulated by the specification, but thanks to the Bypass mode, such modules are capable of working in Socket AM5 and LGA1700 platforms that are not familiar with the CUDIMM standard. That is, users who plan to switch to Arrow Lake processors in the future can purchase CUDIMM modules in advance and use them in existing systems.
A nice feature of CUDIMM modules is that their cost is almost the same as that of unbuffered modules. As with regular overclocker DDR5, CUDIMM uses the same set of components and a similar 10-layer PCB. Only the clock generator itself adds to the price, but this is a penny element, the price of which is lost against the background of the cost of memory chips. As a result, the G.Skill Trident Z5 CK 48GB DDR5-8200 CUDIMM module kit, which we will discuss in more detail below, has exactly the same recommended price of $239 as a set of regular unbuffered G.Skill Trident Z5 modules of similar capacity and frequency.
However, CUDIMMs also have certain disadvantages. Adding additional buffers to the lines between the processor and memory has a negative effect on latency in any case. This is the case with CUDIMMs. And although memory manufacturers talk about only a slight increase in latency, which is almost not felt in the system performance compared to regular unbuffered modules, it is important to understand that the main task that CUDIMMs solve is to ensure the stability of DDR5 at high frequencies, and this is exactly what they should be used for. If in a particular system sufficiently high memory frequencies are achievable without adding a clock generator to the memory modules, then it may not be advisable to resort to the services of CUDIMMs. In terms of obtaining maximum performance, the usual overclocker kits of unbuffered modules may be a more preferable option.
⇡#CUDIMM Inside: G.Skill Trident Z5 CK 48GB DDR5-8200 Module Kit
The series of CUDIMM module kits released by G.Skill was named Trident Z5 CK, where the CK suffix indicates that they are equipped with their own CKD (clock generator) chip. This series includes modules with frequencies from 8200 to 9600 MHz, but for the first acquaintance we chose the junior version, so that it would be possible to compare CUDIMM and regular unbuffered modules directly – at the same frequencies and with the same timings.
The G.Skill Trident Z5 CK 48GB DDR5-8200 kit (part number F5-8200C4052G24GX2-TZ5CK), which we received for testing, consists of a pair of 24 GB single-rank modules, designed to operate at a frequency of 8200 MHz with a fairly typical timing of CL40 for such a frequency. The voltage at which the specification guarantees stable operation is 1.4 V.
The full passport specifications are as follows:
- A set of two DDR5 CUDIMM modules, 24GB each;
- Operating mode DDR5-8200;
- Timing 40-52-52-131;
- Voltage 1.4 V;
- Support for Intel XMP 3.0 profiles;
- Glossy black heat dissipators;
- Lifetime warranty.
The specifications listed above are almost identical to those of another memory kit, the G.Skill Trident Z5 48GB DDR5-8200, which consists of 24GB of unbuffered DDR5-8200 modules. The only difference is the operating voltage: for CUDIMM, it is slightly higher — 1.4 V versus 1.35 V for unbuffered UDIMM modules. And the coincidence of the characteristics is not surprising. For any high-speed 24GB modules, there is only one suitable element base today — SK Hynix M-die chips. Their use in both kits determines the similarity in operating parameters.
In theory, CUDIMM modules should win in supported frequencies, but we took the junior version in the G.Skill Trident Z5 CK series, and it works at a frequency that (under favorable circumstances) is also available to regular modules. But all other versions of such memory have higher frequencies, and they have no analogues among the usual G.Skill Trident Z5 kits.
But there are some nuances in our case as well. The description of the Trident Z5 CK 48GB DDR5-8200 kit, consisting of CUDIMM modules, says that it is designed for systems based on Intel Core Ultra 200 K-series processors and motherboards with the Z890 chipset. In fact, this is a bit of an exaggeration: CUDIMM modules are fully compatible with any representatives of the Arrow Lake family, not only in Z890 motherboards, but also in boards on the B860 and even H810 chipsets. But in any case, it should be borne in mind that there is no full support for CUDIMM modules in the LGA1700 and Socket AM5 platforms, and they will work in them without turning on the clock generator – in Bypass mode. However, despite all this, the CUDIMM kit in question has a much longer list of compatible boards than a similar DDR5-8200 kit made of unbuffered modules. Apparently, adding a clock generator to the modules really solves the stability problems well. According to G.Skill, the Trident Z5 CK 48GB DDR5-8200 kit should work in almost any platform on the Z890 chipset, and for similar memory G.Skill Trident Z5 48GB DDR5-8200, you need to select special overclocker motherboards with high-quality DIMM slots.
The CUDIMM kit in question comes with two XMP profiles. The first profile has the parameters that match the specification: 8200 MHz frequency, base timings of 40-52-52-113, and tRFC2 and tWR delays of 903 and 123.
The second profile is more conservative and is apparently designed for systems without full CUDIMM support. It has a DDR5-6400 mode with primary timings of 32-39-39-102 and tRFC2 and tWR delays of 704 and 96.
The two screenshots below show what kind of delays actually occur when activating a particular profile.
XMP1: DDR5-8200
XMP2: DDR5-6400
A few words should be said about how the modules included in the G.Skill Trident Z5 CK 48GB DDR5-8200 kit look. On the one hand, they do not have RGB backlighting, and smooth heat-dissipating plates are used to dissipate heat, which are very similar in shape to the radiators of any other G.Skill Trident Z5 memory. But on the other hand, the CUDIMM memory stands out due to the black glossy coating of the heat dissipators, which is very reminiscent of piano lacquer in texture. This coating looks very impressive, but it collects dust and fingerprints well, so it is not surprising that a cloth for wiping them is included in the delivery set with the memory modules (but gloves would not hurt either).
It is also interesting to look under the radiators. The entire element base of each Skill Trident Z5 CK 48GB DDR5-8200 strip fits on one side of the ten-layer printed circuit board.
It houses eight 24Gb (3GB) DDR5 chips from SK Hynix, a power controller, and a clock generator (bottom middle) – a new element that distinguishes CUDIMMs from the usual unbuffered UDIMMs.
⇡#Overclocking CUDIMM
The whole theory stated above suggests that the presence of a clock generator in CUDIMM should improve the ability of such memory to work stably at high frequencies, i.e. add additional overclocking potential to it. Therefore, we began to get acquainted with the G.Skill Trident Z5 CK 48GB DDR5-8200 kit with overclocking experiments.
It is well known that the overclocking ceiling of conventional unbuffered DDR5 modules based on SK Hynix M-die chips on successful motherboards is at 8400 MHz. Further overclocking usually stumbles on instability, which occurs not so much because of the frequency limit of the chips, but because of the negative influence of interference and signal integrity violations on the way from the processor to the DDR5 chips. This problem is exactly solved by the additional clock generator in CUDIMM.
Therefore, it is not surprising that the G.Skill Trident Z5 CK 48GB DDR5-8200 kit under review easily overclocked much more – to DDR5-8800. Reaching such a frequency required only a slight increase in module voltage to 1.45 V and weakening the timings to 42-54-54-140.
Note that these timings were even slightly more aggressive than those that G.Skill claims for “real” DDR5-8800 CUDIMM modules. Moreover, to achieve such a memory frequency, we did not have to switch the memory controller mode in the processor. As with DDR5-8200, with DDR5-8800 it worked in Gear 2, that is, using the most effective ratio between the controller and memory module frequency of 1:2.
As a result, overclocking allowed us to get a rather noticeable increase in practical throughput according to the Aida64 Cache & Memory Benchmark. And this means that the overclocking capabilities of the G.Skill Trident Z5 CK 48GB DDR5-8200 kit should be attributed to its undeniable advantages. In this case, we are talking about a very tangible improvement in the memory subsystem indicators, which can be obtained absolutely free of charge – just by setting the BIOS.
However, we will look at what all this results in in terms of real performance a little later.
⇡#Description of the test system and testing methodology
Since full support for CUDIMM modules is currently implemented exclusively in the LGA1851 platform, today’s research was carried out on a system based on the Core Ultra 9 285K processor. Using this platform, as well as a set of G.Skill Trident Z5 CK 48GB DDR5-8200 CUDIMM modules, we will answer several questions about the features of DDR5 modules with an additional clock generator:
- What is the performance gain of DDR5-8200 CUDIMMs over regular DDR5-6400 on Intel Arrow Lake processor-based systems?
- How much slower is a system with CUDIMM modules compared to regular UDIMM modules, assuming equal frequencies and timings?
- Is this damage compensated by overclocking the CUDIMM kit to higher frequencies, such as DDR5-8800?
To answer these questions, we needed a memory kit similar to the Trident Z5 CK 48GB DDR5-8200, consisting of a pair of 24GB unbuffered modules. Unfortunately, we did not have a Trident Z5 48GB DDR5-8200 kit that fully matches the Trident Z5 CK 48GB DDR5-8200 in terms of performance, but we did have a similar kit of UDIMM modules oriented to DDR5-8000 mode, which overclocks to DDR5-8200 without any problems, allowing for a direct comparison with the G.Skill Trident Z5 48GB DDR5-8200 memory.
Thus, we tested the system based on the Core Ultra 9 285K with four memory configurations:
- UDIMM: DDR5-6400 32-39-39-102
- UDIMM: DDR5-8200 40-52-52-131
- CUDIMM: DDR5-8200 40-52-52-131
- CUDIMM: DDR5-8800 42-54-54-140
The full list of components we used in these tests is provided below.
- Processor: Intel Core Ultra 9 285K (Arrow Lake, 8P+16E-core, 3.7-5.7/3.2-4.6 GHz, 36 Mbytes L3).
- CPU cooler: custom liquid cooling system made from EKWB components.
- Motherboard: MSI MEG Z890 Unity-X (LGA1851, Intel Z890).
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- G.Skill Trident Z5 F5-8000J3848F24GX2-TZ5K (2 × 24 Гбайт, DDR5-8000 UDIMM, CL38-48-48-128);
- G.Skill Trident Z5 CK F5-8200C4052G24GX2-TZ5CK (2 × 24 Гбайт, DDR5-8200 CUDIMM, CL40-52-52-131);
- Video card: Palit GeForce RTX 5090 GameRock (2017/2407 MHz, 28 Gbps, 32 GB).
- Disk subsystem: Intel SSD 760p 2 TB (SSDPEKKW020T8X1).
- Power supply: Deepcool PX1200G (80+ Gold, ATX 12V 3.0, 1200 W).
The testing was carried out in the Microsoft Windows 11 Pro (24H2) Build 26100.2605 operating system, which includes all the necessary updates for the correct operation of the schedulers of modern AMD and Intel processors. To further improve performance, we disabled “Virtualization-based security” in the Windows settings and enabled “Hardware-accelerated graphics processor scheduling”. The system used the latest GeForce 572.83 Driver graphics driver.
Description of tools used to measure computing performance:
Synthetic benchmarks:
- AIDA64 Engineer 7.20.6800 – Cache and Memory Benchmark memory subsystem test.
- Geekbench 6.3.0 measures single-threaded and multi-threaded CPU performance in common user scenarios, from reading email to image processing.
- Y-cruncher — measuring the speed of calculating 5 billion decimal places of π using the Chudnovsky brothers’ algorithm.
Tests in applications:
- 7-zip 24.08 – testing compression and decompression speed. A built-in benchmark with a dictionary size of up to 64 MB is used.
- Adobe Photoshop 2024 11.25.0 – testing performance when processing graphic images. The PugetBench for Photoshop 1.0.1 test script is used, simulating basic operations and working with the Camera Raw Filter, Lens Correction, Reduce Noise, Smart Sharpen, Field Blur, Tilt-Shift Blur, Iris Blur, Adaptive Wide Angle, Liquify filters.
- Adobe Premiere Pro 2024 24.5.0 – testing video editing performance. The PugetBench for Premiere Pro 1.1.0 test script is used, which simulates editing 4K videos in different formats, applying various effects to them, and the final rendering for YouTube.
- Blender 4.2.0 – testing the speed of final rendering on the CPU. The standard Blender Benchmark is used.
- Corona 10 — testing the speed of final rendering on CPU. The standard Corona Benchmark is used.
- Microsoft Visual Studio 2022 (17.13.3)-measuring the compilation time of a large MSVC project —blender version 4.2.0.
Games:
- Assassin’s Creed Mirage. Graphics settings: Graphics Quality = Very High.
- Baldur’s Gate 3. Graphics settings: Vulcan, Overall Preset = Ultra.
- Cyberpunk 2077 2.01. Graphics settings: Quick Preset = RayTracing: Medium.
- Marvel’s Spider-Man Remastered. Настройки графики: Preset = Very High, Ray-Traced reflection = On, Reflection Resolution = Very High, Geometry Detail = Very High, Object Range = 10, Anti-Aliasing = TAA.
- Shadow of the Tomb Raider. Настройки графики: DirectX12, Preset = Highest, Anti-Aliasing = TAA, Ray Traced Shadow Quality = Ultra.
- Starfield. Graphics settings: Graphics Preset = Ultra, Upscaling = Off.
- The Witcher 3: Wild Hunt 4.04. Graphics settings: Graphics Preset = RT Ultra.
In all game tests, the average number of frames per second, as well as 0.01-quantile (first percentile) for FPS values are given as results. The use of 0.01-quantile instead of the minimum FPS is due to the desire to clear the results from random bursts of performance that were provoked by reasons not directly related to the operation of the main components of the platform.
⇡#Performance in synthetic tests
It makes sense to start comparing a CUDIMM kit with regular memory with synthetic tests that show practical throughput and latency figures. Usually, such benchmarks give a clear picture of what is happening and help explain why certain results are observed in real applications and games.
Let’s turn to Aida64 Cache & Memory Benchmark. The throughput measurements for reading, writing and copying operations are quite indicative – the higher the memory frequency, the higher the result. Increasing the memory frequency from 6400 to 8200 MHz (by about 28%) increases the observed reading speed almost proportionally – by 25%. The writing speed increases by 12%, and copying – by 21%.
But the most important result for us is that the DDR5-8200 CUDIMM module set produces exactly the same numbers in the benchmark as regular unbuffered DDR5-8200 memory. That is, the additional clock generator does not impose any noticeable penalty on the bandwidth. Moreover, the positive side of CUDIMM is revealed during overclocking – when operating in the DDR5-8800 state, such memory allows increasing the indicators in the bandwidth test by an additional few percent. With the usual unbuffered memory, such a trick will not work.
However, the main concern was not the bandwidth, but the latency. But CUDIMM modules are fine with it. Although the theory says that the latency increases slightly due to the buffering of the reference clock signal, we are talking about such a “small” increase in latency that it is not detected by synthetic tests. We specially conducted an extended latency test, measuring in two data access modes, but did not find any practical difference in the speed of CUDIMM and UDIMM kits.
However, the diagrams show that increasing the frequency of memory modules allows not only to increase the throughput, but also to reduce latency somewhat. However, we are not talking about any cardinal changes. DDR5-8200, compared to DDR5-6400, reduces the latency in the memory subsystem by only 5%. And this is quite modest against the background of how much these latencies have increased in Intel Arrow Lake processors compared to Raptor Lake as a whole. In other words, even fast CUDIMM modules do not allow us to reach the 50-60 ns level that we received in the LGA1700 platform.
Let’s check the measurements of the Aida64 benchmark in y-cruncher – a tool for measuring the speed of calculating the number π, which operates on large amounts of data and reveals the complex performance of the memory subsystem well.
Everything is confirmed: CUDIMM modules at the same frequency and with the same timings are at least as good as the usual unbuffered modules in terms of performance. Plus, they can provide some speed boost due to their ability to work at higher frequencies, which is precisely what the clock generator added to them provides.
⇡#Application Performance
Memory bandwidth is far from the main bottleneck in systems on Intel Arrow Lake. Therefore, increasing the frequency of DDR5 modules in itself does not provide a very noticeable increase in performance in applications. This is exactly what can be seen in the diagrams provided in this section: CUDIMM modules overclocked to DDR5-8800 provide only a 3% (on average) acceleration in the execution of resource-intensive tasks compared to DDR5-6400. And even in the most favorable situations, when the contribution of the memory subsystem performance is maximum, for example, during archiving or compilation, the magnitude of this advantage does not exceed 6-8%.
However, for us, another thing is important in the test results: there are no noticeable differences in the performance of the system with UDIMM and CUDIMM modules at the same frequency and with the same timing scheme (DDR5-8200 40-52-52-131). This means that when selecting high-speed modules for Arrow Lake-based systems, CUDIMM modules should be considered on par with conventional memory. There do not seem to be any major pitfalls in this new technology.
Geekbench 6:
Rendering:
Photo processing:
Work with video:
Compilation:
Archiving:
⇡#Gaming performance
However, before making a final verdict, it is necessary to check how CUDIMM modules perform in games. Games are among the tasks whose performance is most strongly affected by the memory system bandwidth. And it is in gaming systems that high-speed memory performs best, although in this case, low latency is more important than bandwidth.
But we should not forget that the duration of delays with the growth of the DDR5 frequency in time expression, as a rule, decreases, therefore high-frequency memory is also appropriate in gaming systems. It is quite natural that the transition from conventional DDR5-6400 memory to CUDIMM modules operating at a frequency of 8800 MHz, according to the conducted tests, allows to increase FPS by 4%.
However, this is a positive, but not very impressive result. In the previous-generation platform, overclocking the memory frequency gave about twice the effect, but in the case of the Arrow Lake system, the CUDIMM modules are not to blame for the more rapid performance increase. As can be seen from the ratio of the Core Ultra 9 285K results with different DDR5-8200 kits – UDIMM and CUDIMM – modules with an additional clock generator do not cause any rollback in gaming performance. When switching from DDR5-6400 to DDR5-8200, a 3% increase in FPS is observed – both in the case of regular memory and when using CUDIMM. Therefore, complaints about insufficient performance scaling here should be addressed directly to the processor, and not to the new memory modules.
As a result, we have that in terms of performance at the same frequency, UDIMM and CUDIMM modules are practically the same, but CUDIMM has better stability at high frequencies. Therefore, for high-end gaming configurations, it is more logical to choose CUDIMM. Even with identical passport characteristics, they will offer a clearly better overclocking potential than regular unbuffered memory.
⇡#Conclusions
It’s rare, but it turns out that CUDIMM technology is a win-win. It improves the stability of DDR5 memory, and as a result, increases the frequency of modules and increases the bandwidth of the memory subsystem without resorting to major changes to the existing ecosystem. There is no doubt that as CUDIMM modules become more widespread, they will be supported by more and more platforms and will eventually become a standard component of gaming PCs and high-end workstations.
Now, only owners of systems based on Intel Core Ultra processors can taste the advantages of this type of modules. We recommend that they pay close attention to memory kits like the G.Skill Trident Z5 CK 48GB DDR5-8200 reviewed in this article. On the one hand, it is no more expensive than a regular DDR5-8200 memory kit of the same volume, and on the other hand, it opens up a much wider field for experiments, primarily in terms of overclocking.
And, to summarize everything that has been said, we will provide a short list of answers to the main questions regarding CUDIMM modules.
What is CUDIMM and how are these modules different from regular ones?
CUDIMM (Clocked Unbuffered DIMM) is a DDR5 memory module equipped with an additional clock generator (CKD). Unlike standard unbuffered modules, CUDIMM provides better signal integrity and stability at high frequencies. JEDEC recommends using modules with CKD at memory speeds above 6400 MHz.
Do I need special slots to install CUDIMM?
CUDIMM modules use standard 288-pin DIMM slots and can be installed in any motherboard that supports DDR5 SDRAM. However, to operate such modules at high target frequencies, CKD support is required from the platform.
What platforms support CUDIMM?
Full support for CUDIMM is currently implemented exclusively in the LGA1851 platform and Intel Arrow Lake processors. The LGA1700 and Socket AM5 platforms can work with CUDIMM modules only in Bypass Mode – without using an additional clock generator and at lower frequencies.
Do CUDIMM modules improve system performance?
CUDIMM are more stable at high frequencies and have better overclocking potential. This allows achieving higher memory subsystem bandwidth, which can be converted into a performance gain (but its value depends on specific tasks).
Does the additional CKD in CUDIMM increase the latency of the memory subsystem?
In theory, yes. But the effect is so small that it is impossible to notice in tests and real-world tasks. With the same frequency and timing settings, CUDIMM modules and regular UDIMMs provide the same performance.
How to configure CUDIMM in BIOS?
CUDIMMs are configured in the same way as regular DDR5 modules. CUDIMMs support automatic configuration via Intel XMP 3.0 profiles, but you can set the frequency and timings manually if desired.
How much more expensive are CUDIMMs compared to regular DDR5 modules?
CUDIMM modules and regular modules with the same specifications are usually the same price. However, faster CUDIMM modules may cost more.