Introduction
CUDIMM, or Clocked Unbuffered Dual In-Line Memory Module, is a type of DDR5 memory that integrates a clock driver (CKD) chip directly onto the memory module itself. This allows the electrical signal to be improved, thus allowing the memory modules to achieve very high memory speeds, Mega Transfers per Second (MT/s) at stable frequencies. We have one such memory kit to review today, the G.SKILL Trident Z5 CK RGB DDR5-8400 CL40-52-52-134 1.40V 48GB (2x24GB) memory kit. This is G.SKILL’s high-end offering in its Trident Z5 CU-DIMM series.
In G.SKILL’s memory lineup, it offers both traditional DDR5 U-DIMM memory modules and the new DDR5 CU-DIMM modules. G.SKILL has a plethora of well-known series of DDR5 RAM, with probably two of the most well-known series in the flagship Trident series and the Ripjaws series. Among the Trident series are sub-series of memory modules, such as the Z5 CK RGB and Z5 CK (the CUDIMMs we are reviewing today), Z5 Royal, Z5 Royal Neo, Z5 Neo, and Z5. These different series have some with RGB, and some without, and vary in heatsink color and style. As you would imagine, the Z5 CK RGB specifies the use of a CKD chip to tell you that these are CUDIMM memory modules. If you want the non-CUDIMM, i.e. U-DIMM, the other Z5 models below this are UDIMM versions.
It should also be noted that certain models are geared more for Intel/XMP, while others are geared for AMD EXPO. The Trident Z5 CK RGB and Z5 CK are made for Intel Z890 motherboards and Intel Core Ultra CPUs, as they support CUDIMM memory modules and high-speed DDR5. The Trident Z5 Royal is also meant for Intel/XMP. The Z5 Royal Neo and Neo are geared for AMD EXPO speeds, while Z5 is Intel/XMP. Of course, you can run XMP profiles on EXPO motherboards, but you can’t run CUDIMM’s yet on AMD motherboards, and high frequency isn’t guaranteed.
Under the Trident Z5 CK RGB (DDR5/Intel XMP) category on G.SKILL’s product page, there are five kits offered at different speeds. Note that all five kits are of the 48GB (2x24GB) capacity configuration, and all are CU-DIMM memory. The speeds offered are 8200MT/s (CL40-52-52-131), 8400MT/s (CL40-52-52-134), 8800MT/s (CL42-55-55-140), 9000MT/s (CL42-56-56-144) and even 9600MT/s (CL46-58-58-153) memory. All memory kits have the same design, with RGB. The memory kit we are reviewing is: F5-8400C4052G24GX2-TZ5CRK.
G.SKILL Trident Z5 CK RGB DDR5-8400 48GB
The G.SKILL Trident Z5 CK RGB DDR5 8400MT/s CUDIMM 48GB memory series is G.SKILL’s flagship CU-DIMM DDR5 memory series with a glossy piano black heatspreader and RGB. G.SKILL claims hand-selected memory IC’s and that this memory is built for overclockers and enthusiasts. It is designed for Intel Core Ultra 200K series desktop CPUs and Z890 chipset motherboards.
The memory is DDR5 in a dual-channel kit and supports Intel XMP 3.0. It runs at 8400MT/s in Profile 1 XMP mode and has timings set at CL40-52-52-134 in Profile 1. It runs at an XMP voltage of 1.40V in an Unbuffered format Non-ECC. Its default SPD Speed is 6400MT/s on Intel Core Ultra CPUs (non-Plus series). The SPD Voltage is 1.10V. G.SKILL has a QVL list and links on its website.
The box isn’t your typical memory box, but instead it is a nice thick box that opens on a hinge and has the memory inset in protective material; the whole box is wrapped in a sleeve. It is a very premium box experience. Opening the box, you’ll find a QR code to look up how to set XMP mode. The memory kit also includes a soft cloth to keep the piano black and clear of smudges, which is a nice addition, as well as a G.SKILL badge.
The heatsink is an aluminum alloy heatspreader design with a sleek aesthetic design. It is electroplated and polished in a piano black mirrored finish. Atop the RAM is an RGB light bar that is fully customizable with control software or supported third-party motherboard software. You almost feel like handling this RAM is forbidden, because you don’t want to smudge it up; it’s so shiny! Thankfully, we have the provided cloth, and once it is installed in your computer, it won’t gain smudges anymore and looks fantastic.
The RGB is beautiful on this RAM kit and is fully customizable. Inside a computer build, this memory looks great with that mirror piano black look, it is quite unique.
XMP Memory Profiles
Inside this memory, there are two built-in XMP profiles, Profile 1 and Profile 2.
In XMP Profile 1, the memory runs at 8400MT/s CL40-52-52-134, and in Profile 2, it runs at 6400MT/s CL32-39-39-102. Profile 2 is basically a faster timing SPD or default memory frequency mode. For example, in the default (no XMP profile selected) mode, it runs at 6400MT/s CL52-51-51-102. Therefore, Profile 2 offers a much faster 6400MT/s default mode that sets the RAM down to much tighter and faster timings.
In the screenshots above, you can see the first screen at Default 6400MT/s with no profile selected, then in the second screenshot, XMP Profile 2 is enabled at 6400MT/s with faster timings. Finally, the third screenshot shows XMP Profile 1 enabled at the overclocked 8400MT/s CL40 setting.
For a closer look at the timings supported at lower frequencies, you can see those listed here in this screenshot above for this memory kit.
Overclocking
For our overclock testing, we simply tried to push it up as far as possible without changing the Voltage or any power settings at all, by simply raising the frequency in the BIOS. In doing this, we were easily able to take this RAM up to DDR5 8800MT/s at only slightly higher timings, CL42-55-55-141. It was as easy as upping to DDR5 8800 in the motherboard BIOS, and this RAM just worked, with no issues, and without having to raise the Voltage.
It is possible it could run higher, with looser timings, and potentially higher with tighter timings when adding Voltage or tweaking power settings. This RAM seems quite capable of being highly tweaked by enthusiasts and overclockers; it is, after all, built for it. For our overclocking today, we’ll go with this stable, no-voltage-added overclock in our benchmarks just to show it above the built-in Profile.