XPS 8940, unsuccessful Crucial RAM upgrade

Hi

Can you return them and buy from Kingston or Mr Memory?

Thanks Anne,

My purchase was from an EBAY seller that accepts returns, though I haven't checked if apparent incompatibility is grounds for a return. 

And regarding Kingston or Mr Memory, I wasn't aware they would be considered preferred over Crucial, who apparently guarantees their sales.

Thanks again

I just ran the Crucial Scanner on my PC. This is the only 64GB (2x32GB) they now have:

It seems that is what you bought?

I'd return it as DEFECTIVE and get it from Crucial (yeah, I'm sure it costs more). Especially as Crucial says that is the one for your PC.

@Pookie2023​  There's been issues with Crucial in some newer Dell's.

Compatible RAM has included:

1. Samsung
2. Micron (Though they make Crucial.)
3. Dell OEM
4. SK Hynix  (One of Dell's OEM's, though I've had them fail.)

I'm not 100% sure about Kingston compatibility, but I do know to avoid their KVR (Kingston Value RAM).  It's been hit or miss in Dell's.  Their regular RAM seems to be ok.

Besides Crucial, A-Tech RAM has a lifetime warranty and guarantees compatibility.  I've been using them for 10 years now.

Thanks Brad,

Bing Copilot (for what it's worth) seems to agree with your notes regarding compatible RAM. Copilot is also suggesting that:

• The i5‑11400 memory controller is weaker than the i7/i9

• Dell’s BIOS is extremely rigid

• 32 GB DIMMs require tighter subtimings

• Dell cannot relax those timings

So Copilot's suggestion is going with a 32gb kit such as:

Crucial JEDEC 2666 — CT2K16G4DFD8266

Crucial JEDEC 2933 — CT2K16G4DFRA32A

Samsung 32 GB Kit — M378A2K43CB1 (or similar) DDR4‑2666 or 2933

Micron 32 GB Kit — MTA16ATF2G64AZ (or similar) DDR4‑2666 or 2933

✔️ 16 GB DIMMs use mature, widely supported DRAM dies

✔️ Their JEDEC tables are conservative

✔️ Dell’s BIOS can train them easily

✔️ The i5‑11400 handles them without stress

❌ 32 GB DIMMs use newer, higher‑capacity dies

❌ They require tighter subtimings

❌ Dell cannot adjust subtimings

❌ The i5‑11400 memory controller struggles with them

So according to Bing Copilot, the issue is not density in the “chip count” sense, but density of the DRAM die and the subtiming requirements that come with it.

Hi

https://investors.micron.com/news-releases/news-release-details/micron-announces-exit-crucial-consumer-business

Crucial is stepping back from the "retail" area of the market, therefore the current offerings are likely to diminish.

Also finding substitutes.

@Pookie2023​ 

I'm using the Crucial Crucial CT16G4DFD832A, 2 or them for 32GB's... Bought 2 different times on Amazon (they don't seem to have them now?). Running  fine in Dual Channel mode. Only 2 slots available, but I'd suspect the dual 32GB's package from Crucial would work, and they do support it. Still pretty sure you might have gotten defective sticks.

@anne_droid​ Thanks Anne, I'm going to start the return process and hop on getting something asap.

@ispalten​ At Thanksgiving a 32gb Crucial kit was selling for $145 new and by Christmas it was $192new. So although I was shopping for 32gb, I figured if I could get a used 64gb kit for a little more I might save some hurt down the road, but I won't spend $380 for a new 64gb kit given I bought my XPS 8940 I5-11400 for around $500. I doubt my seller has another used 64gb kit, but if they do, I'd be willing to try it. Otherwise, I just saw an 8gb Micron module that matches mine for $40 free shipping and 30-day returns. I'm assuming that would be the most likely RAM to be compatible and, in the future, I'll look out for a couple more identical sticks to get me to 32gb (4x8gb) if I feel I need it.... 

@Pookie2023​ 

I'd assume the price increase is due to Tariff increase, these come from China I think?

Dell will only list Memory configurations that they test.

You could either just buy a 16GB stick and add it to the 8GB stick. It should work. Don't worry about Dual Channel, the performance increase due to Dual Channel is not significant.

You only have 2 slots on the 8940 (I recall, have only looked at motherboard pictures) so just get 2 16GB sticks now. When I got my XPS8940 it too had only 8GB's... and I moved to dual 16GB sticks for 32GB's. A large improvement.

No, it's AI, not tariffs driving up RAM prices and availability.

@ispalten​

I didn't realize I could add one 16gb module to an 8gb module - sounds like one more inconsistency that could result in incompatibility, but what do I know?  So I went ahead and purchased an identical 8gb stick that matches my original one, $35 after taxes and shipping with returns.

BTW, my 8940 has 4 slots so assuming, fingers crossed, this second stick works, but I need more memory, I could add two more sticks, and according to your suggestion, they could be any size.

@Pookie2023​ 

Sorry, I didn't open my case, but Googled for motherboard pictures... from a small picture saw only 2 black slots, so assumed 2, when it is actually to pair of channels, for 4. slots.

I only mentioned the 8 and 16GB's as I tried that out and it did work. "Work" doesn't mean it is at optimum speed, and/or in certain instances it would not fail.

I now have 2 16GB sticks in one of the match pair channel, white I think?

HWInfo shows me this:

@ispalten​ Initially when I saw your clock reading of 1463.1 Mhz, I thought something was wrong with your system, but evidently you have to multiply that by two which equates to ~2933 Mhz which is what my task manager is suggesting I'm getting.

So, it looks like your 16gb modules work, and my second 8gb module that was delivered the other day is working flawlessly, but it's good to have your 16gb specs; in case I decide to add or replace my modules, I would shoot for yours or others noted to work by Dell here.  Thanks again.

@Pookie2023​ ,

@ispalten​ 

1. So, it looks like your 16gb modules work, it's good to have your 16gb specs; in case I decide to add or replace my modules, I would shoot for yours

2. and my second 8gb module that was delivered the other day is working flawlessly, 

1. Correct. Dell's have always been particular about their memory DIMMs (it's running very fast). I would not try more that 32gb (16gbx2). You now have his exact part numbers for a full-bank of memory (that's 2 slots on this machine). I think you both have XPS-8940.

2. Good. Yes, 16gb should be fine for your use-case. Since you now (reportedly) have an "exact matching pair" they should be running in the preferred (high performance) Dual-Channel Mode.

I've found that the best way to verify 100% compatibility with DIMMs in any computer is to run (self booting) www.memtest86.com on it. If it can get through at least 3 long passes with 0 errors, you are good to go.