Are there any issues with CUDIMM RAM compatibility?
Are there any issues with CUDIMM RAM compatibility?
I've recently assembled a new system featuring a Core Ultra 7 265K CPU and an Asus Rog Strix Z890-I Gaming WiFi motherboard. I'm installing 64GB of Kingston CUDIMM DDR5 RAM, split into two 32GB modules. Upon power-on, a yellow LED lights up and the system doesn't enter POST. I've verified the CUDIMMs are correctly installed and cleared the CMOS. I've applied the latest BIOS update and reset the CMOS. According to the manual, CUDIMMs require training before first boot, which might take some time. Despite this, I waited four hours without any issues. I also tested each CUDIMM individually in slot A1, but none worked. All parts are brand new. Anyone else have similar experiences? Thank you.
If it's a Q-LED, yellow indicates a problem with RAM. It doesn't immediately confirm the RAM is faulty—it suggests MoBo can't communicate with it. The issue might be with the RAM itself or with MoBo.
Also, what transfer speed is your RAM rated for? Examples include 6600MT/s, 7000MT/s, 8000MT/s, 9200 MT/s, etc.
Here is your MoBo memory QVL list:
link: https://rog.asus.com/motherboards/rog-st...vl_memory/
Just enter your RAM part number and check if it appears.
I checked a bit, and it seems your MoBo doesn't support any Kingston 2x 32GB CUDIMM RAMs. At least, Asus hasn't listed any that would work. There is one Kingston CUDIMM that's 64GB but it's a single DIMM and operates at 6400 MT/s.
I'm using 64GB of Kingston CUDIMM DDR5 RAM (32X2).
Got a link to the ram kit you're working with? Just an FYI, CU-DIMM's come with an advertised speed, not a guaranteed speed you can hit out of the box with a bunch of parts strung together.
Asus Rog Strix Z890-I Gaming WiFi motherboard
To add, I don't see anything come up when running the geneirc info you'd included into the motherboard's memory QVL, here;
ROG STRIX Z890-I GAMING WIFI | ROG Strix | Gaming Motherboards｜ROG - Republic of Gamers｜ROG Global
ROG Strix Z890-I Gaming WiFi is ready for Advanced AI PCs. It makes builds soar with 10+2+1+1 power stages, hyper speed DDR5 support and the latest PCIe® 5.0
rog.asus.com
I've loaded latest BIOS update and cleared CMOS.
For the sake of relevance, please mention the BIOS version you're currently on for your motherboard.
Moved thread from Components section to Memory section.
Speed is 6000
P/N
Model KVR64A52BD8-32 appears in the memory support database for this motherboard. I verified this before purchasing the RAM.
Asus told me it's typical for the yellow Q LED to stay on during CUDIMM training.
I’ve assembled SFF rigs using Asus Z490-I and Z790-I boards, which booted with Corsair Vengeance and Dominator RAM without issues.
Please be aware that I just checked the QVL for the Z890-I (and B860-G) for Kingston RAM and received 'No Result Found'. Before buying, I located these CUDIMM units in the QVL and saved their P/N from the QVL to a Word document, then pasted the P/N from the Kingston CUDIMM below for reference.
I’m finding this increasingly intriguing.
I revisited the Z890-i QVL and entered only Kingston and CUDIMM details (without GB or speed), and my RAM showed up instantly.
Later, when searching for Corsair Vengeance CUDIMM, I used vendor, size, speed, and CUDIMM input, but no results appeared. After adjusting size and speed, both Vengeance variants reappeared in the QVL.
CUDIMM is only suitable when the transfer rate reaches 6600 MT/s or above. For rates between 4000 and 6400 MT/s, standard UDIMM performs adequately. In my two projects (details in my profile), I used regular UDIMM. At 6400 MT/s with CL32, Kingston Fury Beast RGB 2x 16GB set [KF564C32BBEAK2-32]. For you, your setup is Kingston ValueRAM series RAM – the lowest quality option. This also accounts for the very high CAS Latency and explains why CUDIMM only raises its cost without justification. Also, your RAM is individual DIMMs, which is mentioned in the Kingston specifications. Therefore, you’ve combined two separate DIMMs and attempted to use them together, which is not recommended. The reason for this issue is highlighted in the forum thread: https://forums. For testing purposes, remove the second DIMM and test one at a time to see if the build starts up. It might be worth trying both DIMMs separately. I found out about the Kingston Fury Beast RAM (UDIMM) [KF552C40BWAK2-64] in a 2x 32GB DDR5 5200 MT/s configuration: https://pcpartpicker.com/product/3X...-3...40bwak2-64 This model is confirmed in your memory module QVL to function at 5200 MT/s when both DIMMs operate together. When RAM DIMMs are developed, they are tested together, and compatible pairs are grouped into sets. Initially, an 8-stick set is sold as a single package. If that fails, it’s split into two groups of four. If those work, they’re packaged as four sticks each. If only two stick pairs cooperate, they’re sold as two pairs. Only the best pairs are offered as single units. If your two individual sticks don’t work together, consider buying a complete RAM package instead.
Aecus,
Your detailed response was appreciated. I attempted each CUDIMM in Slot A1 and received the same outcome—no yellow light detected. I’ve also ordered a Corsair Dominator 5200 16GBX2 and am awaiting its delivery. Should it function, I’ll confirm later and wrap up the thread. Thank you for your patience.
Attempt them in B1 too. Because while A1 is preferred, it sometimes fails, so you have to use the second slot. If it works in B1, you realize it's a MoBo problem and A1 is bad. If it still doesn't work, hold off until more RAM is available.
Installed Corsair Dominator 16GBX2 DIMMs.
Computer started up in BIOS right away.
Windows 11 installed successfully.
System is now prepared for setup.
Issue fixed.
Appreciate your help and detailed feedback.
This is incorrect. The issue concerns the JEDEC specification and requires a CKD for every JEDEC speed beginning at 6400, and above that as well.
Understanding that it is a JEDEC standard clarifies that latency isn't related to the brand.
If this deviates from the JEDEC specifications, I would accept your position, but since it does not, it is invalid.
All timing and subtiming details must remain consistent, ensuring compatibility regardless of memory type.
Using any binned memory with XMP/EXPO profiles guarantees proper alignment.
It's good to hear the system is operational. I wanted to mention that performance is quite limited, especially if your setup relies heavily on memory capacity. Intel's ARL is a step down in terms of memory latency, so choosing DRAM should focus on speed and low latency. Right now the prices are quite high, making it unlikely you'll be able to afford such memory. Generally though, you'd aim for at least DDR5-6000, with no more than 6000/CL36, 6400/CL38, or 6800 (or better) paired with CL40. DDR5-7200 CL34 (1.4v or below) remains the best option for low latency and solid speed, and it should also work with 200S Boost without needing to adjust CPU settings.