XPS 8940, memory upgrade of 2x8GB

The best I can tell you is do not mix memory, only have one brand/type.  We see lots of problems from users who try to mix memory.   Dell's also have a long history of memory compatibility with non Dell OEM memory.  Some will work in one and not another of the same model.  For this reason, we suggest Crucial for non Dell OEM memory as it is guaranteed to work in a Dell.

Memory RAM & SSD Upgrades | dell | xps | XPS 8940 | Crucial.com

@Lar77 Are you sure that your 16GB memory configuration is 2x8GB and not 1x16GB? You can check by opening the case or running a program like CPU-Z. 

In the past, not all memory configurations that work are listed in the Dell specifications, the configurations listed are those that Dell has tested or shipped. It may help to search this forum to see if someone has tried the configuration you are interested in.

Also, you may want to look at this thread: https://www.dell.com/community/XPS-Desktops/XPS-8940-SE-third-party-RAM-cannot-run-at-2933MHz/td-p/7729441

The last post in that thread is interesting because it mentions a Crucial 2x8GB kit. I am not sure how the poster searched userbenchmark.com to find that information without looking at each of the 970 XPS 8940 systems that were benchmarked..

Re: even though the specs says the system doesn't support it

that is just a miss in spec

you will be fine running 4x8 Gb in dual channel.  Ideally get identical 2x8 gb with exactly the same model number as original pair.  If too expensive to get it from Dell (usually at premium price), get Crucial ram as already suggested with same speed (MHz) as original pair, then install in dual channel, meaning DIMM1/3 for AA, DIMM 2/4 for BB.

Thank you @fireberd , I'll look into Crucial memory, the Dell memory is vey expensive. You think 4 x 8gb ram will work, even though it's not listed as an option in the Dell spec?

Thank you @redxps630 . Yes, the Dell ram is very expensive. I'll look at getting 2 more 8gb from Crucial with the same spec. Thanks!

@Vic384 Thank you for the info & link.

I haven't actually received the PC yet, it's due to be delivered early next week. The spec is for 2 x 8gb so I would assume that's what it will be, but I will open it and double check before I buy ram. I guess one 16gb stick in there would help me ... 

I did look for anyone who had 4 x 8gb ram in the 8940 but wasn't able to find any post.

Hi,

I have replied to you via a private message.

-Gautam.

Another thought.  Unless you have a specific application for that much memory, what you have will suffice.  I use my desktop with 16GB of RAM in my recording studio.  Even with a big recording project with a lot of MIDI I've never seen the memory usage go over 9GB RAM.

@Lar77 If you know the Service Tag you can view the system configuration at https://www.dell.com/support/home/en-us

The system configuration lists the Dell part number of the memory module(s) and the number of modules in the system. Looking at the Dell sales site for the XPS 8940 I see both 2x8GB and 1x16GB are available.

I should have 2 sets of Crucial Ballistix 16GB Kit (2 x 8GB) DDR4-3600 Desktop Gaming Memory (White) (BL2K8G36C16U4WL) in either today or tomorrow, I'll throw them into my XPS 8940 and let you know what happens if your still waiting on a response. I'm running into issues with running out of ram and ordered these without doing my research first. Worst case scenario, I'll just return one set.

https://www.crucial.com/memory/ddr4/bl2k8g36c16u4wl

Everything went well, (XPS 8940) I attached a picture with all my system information and the memory is running at 2666 MHz. Not preferable, but Dell being Dell, that can't change. It made a world of difference in benchmark testing, I went from 83% to 97%. I changed the RAM from 16x1 Dell to the previously mentioned 4x8 Crucial RAM, no issues booting, everything has been running perfectly. Went ahead and bought the memory with the intentions of being able to use it on future builds instead of buying pre-made machines like I always have in the past. 

@jjmax0789 This is helpful to others who may wish to use this 4x8GB configuration. I wonder why the memory is running at 2666 MHz and if it would do that with a 2x8GB configuration.

After reading through all the other posts, that's a Dell thing. They don't allow XMP adjustments to the RAM in the BIOS setup, so that's what I am stuck with. Even though there's plenty of people saying that the MHz being lower is not as bad as it sounds. I didn't do my research before buying the 8940, and I wouldn't say I regret it (it's really a great machine) but I don't like not being able to make improvements to their full capability. So far I upgraded the CPU cooler with the Noctua NH-U9S heatsink, changed out the exhaust fan for the Noctua NF-A9 PWM fan, and added another one to the front. Unfortunately I did not get the K version of the i7-10700, so I got the little cooler that reportedly underperforms. And then of course, the RAM. 

I will run a benchmark at 1x16, 2x8, and 4x8 and post results later tonight because I know that everybody looking for this information in the future when looking through these posts. I imagine they will still run at 2666, but we will find out!

@jjmax0789 You are correct that Dell does not support XMP adjustments so it is important that the SPD in your particular case is at least 2933 MHz or greater. With your Crucial RAM it is likely that the SPD is 3600 MHz although it is not listed in the specs. This makes me wonder if there is another reason why you are only getting 2600 MHz.

Well I am open to suggestions if you have any!

What are the negatives to operating at 2666? I am new to all of this and learning as I go.