Z890 Extreme / 285k with Corsair Cudimm 8400 XMP?

[Aragonite]

A while ago (maybe 2-3 months), I tried these Corsair memories:

CORSAIR Vengeance RGB DDR5 CUDIMM 48GB (2x24GB) 8400MHz CL40-52-52-135 1.4V

No issues without XMP, but once it was enabled, I had game crashes.

So I tested my sticks with MemTest, and it found errors (only with XMP enabled).

Do you know if the latest 1901 BIOS has improved stability so I can try again?

[XBrookieX]

Unfortunately not, or not for me. found the boost  and XMP to be very hit and miss.

Core boost off and XMP disabled my PC is stable but obviously a little underwhelming . Activate the new core boost that also switches XMP to 1 causes all sorts of issues that relate back to Ram. trying out XMP 2 at moment. funny thing OCCT stress test pass. Hope Asus got a New bios in the works as 1901 hasn't made mine any better.

I have CUDIMM 8000 and tested with older 6600 same issues. Madness for the amounts of money we all spent.

[XBrookieX]

Glad you managed to get sorted, it's an expensive Nightmare. 

I too think I've cracked it a the moment although not to the speeds I should have. 

XMP profile 2 bios 1901 and NVME to auto not Gen 5 although my T705 are G5. 

Had to turn off 200s boost. Put that on and stability is luck of the day. 

Hope intel and Asus working on some kind of wizardry. 😁

Annoying removing 64 GB 4 stick RAM for 2 Sticks 48Gb on a extreme MB to allow XMP or super boost is a real design floor or bad software engineering. 

If that New chip is going to be 285 chip refresh intel should admit failure and give mass discounts for a step up program like Samsung. 

[XBrookieX]

2006 Bios out, fingers crossed this one is better.

[dviper42]

On my Asus strix rog Z890-E with 285k and corsair dominator ddr5 8200 I run it at XMPII 8000 with the 200 boost enabled. Bios ver. 2006 it's stable most of the time but waiting on a windows update from 4770 August Tuesday hopeful fix.

[K1eronm4]

Literally exactly how im feeling bro! Cannot get a stable run for my 8200 cudimm kit, absolute joke for what's supposed to be the next generation, feel like I've wasted money on the motherboard, ultra processor and the cudimm kit. Gonna be looking at a 9800x3d at this point

[dviper42]

I have a z890 rog strix 285k with corsair dominator 8200 XMP II bios 2006 win 11 pro latest version. It's hit and miss it's stable at the moment. I also have X870-I itx with 9800x3d gskill neo ddr5 6400 latest bios nvidia 5070 12G has been running perfectly. No issues. Lots of tweaking on Intel to keep stable 🙄. It's good to have both for comparison

[svukelich]

I have the same motherboard and the same memory. Even though the Corsair website stated that the memory is compatible, I found that it only works at the default speed, 5600 MHz, or set at 6000 MHz. I tried for months to get it to work and was unsuccessful. I broke down and bought the G.SKILL 8400 MHz memory (but not CUDIMM, since it is unavailable) and have been running it at 8400 MHz with no issues.

[Aragonite]

What I don't understand is that most reviews say that these Cudimm memories are "great" and that everything seems to work perfectly with them...

Everything is up to date for me, without changing anything except XMP...

but it found errors...

Without XMP or with my other DDR5 DIMM 7200 (with XMP) no problems!

And it's been going on for months...

[Clyydefrog]

According to the Asus Update Center it says version 1901 is for:

"1.Update Management Engine (ME) to version 19.0.5.1984.

Updating this BIOS will simultaneously update the corresponding Intel ME to version v19.0.5.1984.The ME version will remain updated even if you roll back to an older BIOS later. We recommend using EZ Flash to update the BIOS, as it supports ZIP format and auto-updates the ME. If using USB BIOS FlashBack, ensure the ME version matches the BIOS version and rename the BIOS file with BIOSRenamer before proceeding.
Before running the USB BIOS Flashback tool, please rename the BIOS file (A5555.CAP) using BIOSRenamer."

So safe to say no, it wouldn't really help your case. 

a quick google search shows a dozen or so reviews with the XMP profile with the voltage at 1.45, which is pretty low for that kind of speed.

On corsairs website https://www.corsair.com/us/en/p/memory/cmhc48gx5m2x8400c40/vengeance-rgb-48gb-2x24gb-ddr5-cudimm-840...  you can see the ram Power Draw is rated at "Extreme OC PMIC" which translates to "Extreme overclocked PMIC supports up to 1.9V on VCC/VDD" That link will inform you that the x in the serial number of your ram means you can set the voltage of your ram up to 1.9v. I have a pair of Dominator Titaniums that have been running at 1.9v on the Z890 Extreme since release and they've never had a problem. I would try that and see if it fixes your problem. If not I would wait until the next BIOS update, could have more stability fixes. It might be worth it to run Dimm Fit in BIOS to get an exact picture on what kind of performance the Ram can output. 

Best of luck!