XPS 8940, memory upgrade of 2x8GB

Most reliable ram so far not from dell IMHO CMW32GX4M2E3200C16

16-16-16-39-55-1T, 2933MHz @1.35v

https://www.corsair.com/us/en/Categories/Products/Memory/Vengeance-PRO-RGB-Black/p/CMW32GX4M2E3200C16

https://www.amazon.com/CORSAIR-Vengeance-3200MHz-PC4-25600-CMW32GX4M2E3200C16/dp/B081XWLQKS/

Ranks have to do with DENSITY not Capacity.

4 slots 128 GIG Max Ram means you don't support Registered or HIGH Density or QUAD RANK.

Mixing Ranks is NEVER supported.

The ram that works is VERY VERY VERY VERY VERY VERY VERY VERY Specific.  You have 4 ram slots and max ram is 128 gigs.       I would NOT advise trying 8 GIG modules if they are quad rank.

Nor do ECC or Registered modules work.

Low density = $expensive

High density = $cheap  doesn't work and cant be returned

LOW DENSITY is REQUIRED.

LOW Density. INTEL Compatible

Hi all.

Yesterday my order of Dell Memory Upgrade - 16GB - 2Rx8 DDR4 UDIMM 3200MHz arrived.

I fitted the new stick (16Gb) into slot 1 and moved the 2  8Gb sticks (that were originally in slots 1 & 2) into slots 3 & 4, leaving slot 2 vacant. (Leaving the 8 Gb sticks in 1 & 2 and adding the 16Gb into 3 gave poor benchmark outcomes)

The good news is that it was an easy task to add the RAM and my Novabench score has gone from 3,841 (RAM component 267, with speed of 25,667 MB/s for 16 Gb) to 3,916 (RAM component 315, with speed of 27,502 for 32 Gb).

I notice that using Speccy, it show the RAM speed for all three sticks as "Max Bandwidth DDR4-3200 (1600 MHz)". 

My questions are:

1. Would I gain an appreciable benefit if I added another Dell 16Gb RAM stick into slot 2, giving a total of 48Gb ?

2. Is it ok to continue with three sticks (1 x 16Gb plus 2 x 8 Gb) and is there any inherent downside to this?

3. Does the Speccy outcome of 1600 MHz mean anything? (I would have expected to see close to 3000 MHz, given the RAM specs.

Any assistance is much appreciated - the help so far has been invaluable for an old amateur like me!

Cheers & thnaks!

Paul

@Leperclown 

I knew you'd only get 1x 16 GB 2Rx8 DDR4 module, not 2x 8 GB as was claimed...

How are you numbering slots, by DIMM#  on the board or by physical slot position, counting from the CPU? Are the two OEM modules in slots with matching retention clips?

Speccy reports max bandwidth, so you have to multiply that by 2, but that probably isn't the speed it's actually running because the XPS 8940 is limited to 2933 MHz, max, regardless of how high the RAM is rated.

You can can check the actual RAM speed with CPU-Z (free). Also check to see whether it's running in single- or dual-channel mode ("Channel #", in CPU-Z), which can impact speed/performance.

Hi RoHe,

many thanks for the input - much appreciated! Below are responses to your questions:

1. I am numbering the slots by the DIMM markings on the mother board
2. The two OEM modules (2x8) are in slots with matching retention clips
3. The 16 Gb stick doesn't have a matching 'partner' - the other slot the same colour is empty
4. I tried to download CPU-Z, but didn't receive the email I was supposed to get to validate my account (this happened twice - personal & work email addresses). I will try to follow up today

Cheers!

Paul

@Leperclown  - You don't need an account to download CPU-Z. You fell for their registration nonsense...

Just scroll down the page I linked above and look for the purple button on the left side marked:  "Setup - English 32 and 64-bit version" listed under Classic Versions.

Click that button and then click Download when the new page opens. The version that's offered is an update from the one I have now and it downloaded here in ~2 sec and I've never created an account. And it installed almost as fast as the downloading...

I'm surprised putting the 2x8 GB OEM modules in DIMM1+DIMM2 (physical slots 2 and 4 from CPU), with new 16 GB in DIMM3 (physical slot 1) gave poor benchmarks.  Be interesting to see what speed RAM is running at in your config...

RoHe,

thank you once again. Following your directions, I downloaded and ran the CPU-Z utility.

I'm not sure if I am reading the correct section, but under the memory tab, it says "DRAM Frequency" 1463.2 MHz

I have ordered another 16Gb memory stick, which will give 16+16 & 8+8 (48Gb total). All sticks are the same vendor (Dell) and have the same specs (except for memory size).

Many thanks for all your help.

Cheers!

Paul

@Leperclown  As the PC uses Double Data Rate (DDR) memory, then the memory frequency is double that given by CPU-Z, or close to the 2933 MHz quoted for the Dell XPS 8940.  So that tells me that your memory is working to spec. without issues and is the same DRAM frequency as CPU-Z gives for my XPS 8940.

---

@Leperclown wrote:

RoHe,

thank you once again. Following your directions, I downloaded and ran the CPU-Z utility.

I'm not sure if I am reading the correct section, but under the memory tab, it says "DRAM Frequency" 1463.2 MHz

I have ordered another 16Gb memory stick, which will give 16+16 & 8+8 (48Gb total). All sticks are the same vendor (Dell) and have the same specs (except for memory size).

Many thanks for all your help.

Cheers!

Paul

---

Glad you got CPU-Z downloaded and it says RAM is running at ~2933 MHz.

What does CPU-Z say for "Channel #" on its Memory tab, Single or Dual?

Hi RoHe,

once again you have provided valuable input! Thank you for your help.

It's great to know that the memory is running optimally at the moment. Adding the 16Gb stick into the empty slot can only improve things again - even if the difference is marginal.

I checked on CPU-Z and Channel # is "Dual" - which I'm guessing is a good thing.

Cheers & thanks!

Paul

Jon-62,

many thanks for your input. It's a relief to know that I was not running at 'half speed".

Cheers

Paul

---

@Leperclown wrote:

Hi RoHe,

once again you have provided valuable input! Thank you for your help.

It's great to know that the memory is running optimally at the moment. Adding the 16Gb stick into the empty slot can only improve things again - even if the difference is marginal.

I checked on CPU-Z and Channel # is "Dual" - which I'm guessing is a good thing.

Cheers & thanks!

Paul

---

After you install that 2nd 16 GB module, run CPU-Z again and check both the speed and Channel #.

And yes, "dual" is a good thing.

@speedstep 

No problems at all? 16-16-16-39-55-1T 2933Mhz? right out of the box? @1,35 v??

Does the LPX model ( no RGB) work the same?

8940 doesn't have xmp  so there is no 1.35v

You are still falling for the MHZ myth cas counts more than Mhz

https://www.gskill.com/specification/165/166/1536654268/F4-3200C16D-16GTZR-Specification

@speedstep 

Thanks for your reply.

Nope i am aware of latency issues, and that XPS 8940 does not support 1,35v, that's why i was asking...
From experience i can add something cheaper;  jedec default (Plug N Play): DDR4-2666 CL16-18-18 @1.2V
It's HyperX HX426C16FB3K2/16