Now that both Samsung and Micron are shipping their 16 Gb DDR4 memory chips to third parties, we're seeing wider availability of 32 GB unbuffered memory modules (UDIMMs). To date, six brands have either introduced, or started to sell their 32 GB unbuffered DIMMs, and in the coming months more manufacturers are expected to follow.

The Basics

Before we proceed, let us recap the basics here. Because of the way memory sub-systems work, high-capacity memory modules (in our case, 32 GB and higher) for workstations and servers are built differently than regular DIMMs for client PCs (which are called unbuffered DIMMs, or UDIMMs). Registered DIMMs (RDIMMs) carry a register chip that buffers the address and command signals, whereas the Load Reduced DIMMs (LRDIMMs) replace the register with an Isolation Memory Buffer that buffers the command, address, and data signals. While both the register chip and the IMB allow hardware vendors to build high-capacity memory modules and memory subsystems, neither RDIMMs nor LRDIMMs work with regular client platforms. Therefore, if you use a contemporary desktop and need a lot of memory for some reason, you'll need 32 GB UDIMMs.

You can read more about contemporary types DIMMs an appropriate article covering different types of contemporary memory modules

At the time of writing, 32 GB UDIMMs are supported by client platforms based on AMD’s 400 and 500-series chipsets as well as Intel’s 300-series chipsets.

The List

Twitter user momomo_us, who is from Japan, has managed to get a list of 32 GB unbuffered memory modules that are either available now or are about to hit the shelves there. The list is valid for Japan, yet we do know that ADATA and G.Skill are about to launch their 32 GB UDIMMs in the near future too, so our list includes data on these memory sticks as well.

There are a number of remarks to be made about 32 GB memory modules. Samsung’s mass-produced 16 Gb DDR4 memory chips are rated for 2133 MT/s, 2400 MT/s, and 2666 MT/s data transfer rates, yet even the company itself sells 32 GB DDR4-2933 memory modules. Meanwhile, its partners go all the way to DDR4-3000, albeit at 1.35 Volts. Meanwhile, the only modules that semiofficially feature Micron’s 16 Gb DDR4 chips are rated at 2400 or 2666 MT/s, at 1.2 Volts.

List of 32 GB Unbuffered Memory Modules Announced
Note: Data is not official
Brand Data Rate
(MT/s)
Latency Voltage DRAM Vendor PN More Info
ADATA 2666 CL19 1.2 V Micron (?) AD4U2666732G19-B -
Asgard 2666 CL16 1.2 V ? ? -
Asgard 3000 CL16 1.35 V ? ? -
Corsair 2400 CL16 1.2 V Micron ? -
Corsair 2666 CL16 1.2 V Samsung ? -
Corsair 3000 CL16 1.35 V Samsung ? -
Crucial/Micron 2666 CL19 1.2 V Micron CT32G4DFD8266.16FB1 -
G.Skill 4000 CL18 ? Samsung F4-4000C18-32GVR -
Gloway 2400 CL17 1.2 V ? ? -
Gloway 3000 CL16 1.35 V ? ? -
Samsung 2666 CL19 1.2 V Samsung M378A4G43MB1-CTD -
Samsung 2933 ? ? Samsung M471A4G43AB1-CVF -

The Modules

Now that we know the specs, let us talk about the modules themselves:

ADATA

What ADATA has shown so far were 32 GB DDR4-2666 CL19 DIMMs at 1.2 V. Considering the clock rate, these modules hardly need a heat spreader, yet knowing the company, we cannot exclude a possibility of enthusiast-class 32 GB UDIMMs with heat spreaders.

Asgard

Asgard’s Loki T2 and W2 memory modules are designed for enthusiasts, so they come with heat spreaders. The 32 GB DDR4-3000 CL16 modules need 1.35 V voltage and therefore need an enthusiast-class platform. Meanwhile, their 32 GB DDR4-2666 CL16 modules use industry-standard 1.2 V voltages.

Corsair

Corsair’s 32 GB Vengeance LPX unbuffered DIMMs come with DDR4-2400, DDR4-2666, and DDR4-3000 speeds. Depending on speed bins, these modules reportedly use memory chips from Micron or Samsung and require 1.2 V or 1.35 V. Corsair’s UDIMMs traditionally rely on the company’s custom 10-layer PCB designed to ensure quality signaling when operating at higher clocks, and are equipped with black heat spreaders.

Crucial/Micron

Micron’s Crucial brand introduced its DDR4-2666 CL19 32 GB UDIMMs back at Computex and these modules are expected to show up on the market shortly. Crucial’s 32 GB UDIMMs do not feature any heat sinks, but use industry-standard voltage, which makes them compatible with a wide variety of PCs.

G.Skill

G.Skill demonstrated its 32 GB UDIMMs at Computex, yet these modules are not available just yet. The company traditionally addresses enthusiasts with its products, which is why the memory sticks are rated for DDR4-4000 CL18 speed and are equipped with red heat spreaders. Given the unique combination of performance and capacity, expect G.Skill’s 32 GB unbuffered DIMMs to cost more than competing products.

Gloway

Gloway’s 32 GB UDIMMs are rated to operate at DDR4-2400 CL17 and DDR4-3000 CL16 speed bins, according to the listing. Depending on performance, the modules need 1.2 V or 1.35 V and come with heat spreaders.

Samsung

Samsung was first to start to producing 16 Gb DDR4 memory chips and was naturally the first to launch 32 GB UDIMMs. At present, the company offers DDR4-2666 CL19 and DDR4-2933 32 GB unbuffered DIMMs that come without any heat spreaders (based on the pictures of the modules from AVADirect).

Related Reading:

Sources: ADATA, Corsair, Crucial, G.Skill, Samsung, Twitter/momomo_us

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  • DigitalFreak - Wednesday, July 31, 2019 - link

    Quick check of Newegg shows that going from DDR4-2666 to DDR4-3200 more than doubles the price on a 32GB stick. Reply
  • extide - Wednesday, July 31, 2019 - link

    Yeah but you can ignore those G.Skill 3200 modules as they are the older double stack 32x8Gb DIMMs. Nothing faster than 2666 using the new 16Gb chips on Newegg, yet. Reply
  • abufrejoval - Wednesday, July 31, 2019 - link

    Looking at those modules reminds me about my troubles trying to buy RAM (nice prices for a change) that can last more than a single generation of machine: With machines getting smaller, mobile, NUC and ITX the traditional DIMM form factor seems rather wasteful in terms of mainboard surface area and yet the extra real-estate on the BO-DIMMs (for BIG outline) vs. the SO-DIMMs doesn't really seem to matter any more: Available traces and TTL loads seem the limit not surface area (except perhaps for cooling some crazy overclocked ones).

    I'd really like to be able to move modules between laptops, NUCs and desktops because sockets are after all there to decouple life cycles. But I cannot find 35/65/95 Watt mainboards with CPU sockets or even soldered SoC that accept SO-DIMMs, except some really special (old and expensive) embedded designs.

    No vendor trying to jump for Mini-ITX and 4 sockets of SO-DIMM? There are back-sides and overlapping mounts for laptops and DDR4-2400/2666 doesn't seem to get that hot anyway.
    Reply
  • Ej24 - Thursday, August 01, 2019 - link

    Check asrock rack. Their server/professional boards are really good and they often have surprising, uncommon options/form factors, like 4x sodimm on an itx board Reply
  • abufrejoval - Tuesday, August 06, 2019 - link

    Yep, but those are LGA 2066 boards, not quite the price range I had in mind :-)

    I am looking for laptop technology in a Mini-ITX form factor for low power/low noise server use and some flexibility in terms of RAM/storage/GPU/cooling configuration at a price below that of the laptop (after all, significant parts are left out). Basically that's what NUCs are, except for the Mini-ITX. Of course I can get a silent case for a NUC at premium prices, but most of the time a Noctual will do well enough: No need for silence, when unnoticeable is enough. A Mini-ITX gives me that choice and if I should need to put a beefy GPU (or some other PCIe card) into the board, I just move it into a mini-tower case: Modularity is wonderful and a PC feature since 1981!

    But evidently I run against the constraints of scale, since my interest is either shared by too few, or someone wants to maintain market segmentation. I basically want Xeon D functionality at Xeon E3 economy. Since AMD pushed Intel to 6, 8 and soon 10 cores on the desktop, the premium on Xeon D/Xeon 2100 is under threat.

    The ECC premium on Intel CPUs and chipsets has almost disappeared over the last years, perhaps because AMD put a pressure point there (alas, without validatiotion too often).

    In some cases that doesn't matter, in others (ZFS) I still don't like taking chances.

    It's a persistent problem in IT: All components are basically there, nobody want to sell them in the permutation I want. Am I being unreasonable?
    Reply
  • PeachNCream - Wednesday, July 31, 2019 - link

    I hate it when the DIMMs aren't buffered. Their floors are a lot more more dull looking. Reply
  • mickulty - Wednesday, July 31, 2019 - link

    I suspect that samsung module picture is an older "stock photo" as it's the A1 PCB layout (shared with D1 ECC) - any new OEM module especially DDR4-2666 and higher I'd expect to be on A2.

    That said it would also be very surprising if there was a heatspreader on a UDIMM, and AVADirect's search function categorises them as no heatspreader so the article's definitely not wrong :-)
    Reply
  • Atari2600 - Thursday, August 01, 2019 - link

    Will these work on X399? (Boosting Threadripper to 8x 32GB = 25GB DRAM) Reply
  • Grayswean - Thursday, August 01, 2019 - link

    Officially: no. Unofficially: probably. Motherboard makers aren't going to validate and support it working, but hopefully someone else will test it out for us. Reply
  • b3081a - Sunday, August 04, 2019 - link

    At least someone has already validated those kits against 2700X on a B350 board. I guess Threadripper won't be worse anyway.

    FYI: https://www.reddit.com/r/Amd/comments/ck0e1o/128gb...
    Reply

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