adding 4gb x2 memory

First of all, in my opinion, Table 2 Memory configuration matrix in the XPS 8910 is wrong including the note above it. The note says use slots DIMM1 and DIMM3 if you need to use two memory module just as the Table shows, but look at the System-board components picture on page 17. DIMM1 and DIMM2 have white colored memory locking tabs and DIMM3 and DIMM4 have black tabs. Matching memory modules should have matching colored tabs. By the way the slots are numbered from the CPU socket DIMM3 (Black), DIMM1 (White), DIMM4 (Blk) and DIMM2 (Wht). Also look at the service manual for the XPS 8920, although the motherboards are different the layout is the same and the Table is correct although the note is still wrong. Check and see how Dell installed the original memory.

Second, I would not be concerned that the memory configuration matrix does not show your configuration. It does not show the configuration of my XPS 8910 as received from Dell. My XPS 8910 came with a single 16 GB module in DIMM1 and I have since added another 16 GB in DIMM2.

Finally, what is the model number of your Kingston memory? I just want to check to see if it is compatible. I would run the test recommended above with the Kingston memory, just make sure to install the modules in the correct slots.

Hi Bill, 

Go ahead and try the new memory by itself and see if the system boots up. Then add back in the old memory to see what happens, typically you want to have all matching memory for 4x4, but as long as the memory is within spec it should work... Let me know if the new sticks at least boot the system. 

Best regards,

Brad

I need look at the manual you're looking at, but typically the reason you want to run in Dimm 1 and 3 is to have dual channel functionallity. That's how it has been since 2500k or so (that's the earliest I can remember, but it might have been even earlier). I know before it used to be 1/2 and then 3/4. So in this case you would want 1/3 matching and then 2/4 matching. The reason for this is 1 and 3 are A1 and B1 and 2 4 are channel A2 and B2. So you want memory in A1 and B1 for dual channel mode or A2 and B2 etc.    

You should check on your system and see if it's in dual channel, there is a good chance it is running in single mode unless you have something in the other slots now.

I hope this helps, and glad to discuss further.

Best regards,

Brad

Thanks Brad,

KCP421NS8/4  2133MHZ DDR4

Thanks vtov116.

In my XPS 8910 the memory modules are in DIMM1 and DIMM2 and according to CPU-Z and HWiNFO64 the memory is running in dual channel mode. Before adding the second memory module these programs reported memory running in single channel mode which is obvious if you only have a single module. By the way if you want 1/3 and 2/4 matching the colors of the memory release tabs would not match which would be against the industry standard..

It looks as if the Kingston KCP421NS8/4 are correct and should work.

I think we're discussing/agreeing on the same thing... the memory next to each other side by side is dimm 1 and 3 so the order is 3/1/4/2 as per the manual away from the proc (now that I looked at it for both 8910/20, I think on the 8910 it's on page 15/16). I was literally meaning that it's identified in the manual as Dimm 1 3 and 2 4 even though in this case they're side by side (which typically would mean 1-4, instead of 3/1/4/2)

I have seen most aftermarket boards that are a bit different though, and are actually in slot 2/4 and 1/3 for pairs (dual channel etc). Here is an example of this on an Asus board here on page 1-5, you'll notice this being the same on a lot of boards too. 

Best regards,

Brad   

Brad,

I am not sure I understand what you are saying. I think we agree on the way the DIMM slots are numbered/labeled, it is identical for both the XPS 8910/8920, I think we also agree the DIMM1 and DIMM2 have white memory securing clips and DIMM3 and DIMM4 have black memory securing clips.

Now let's look at Table 2 Memory configuration matrix. For the XPS 8910 (page 78), the note and the table agree, memory pairs should be installed in DIMM1 and DIMM3; slots with different colored securing clips. For the XPS 8920 (page 76), the note and the table disagree, the table states memory pair should be installed in DIMM1 and DIMM2 and the note states DIMM1 and DIMM3. If you ignore the note for the XPS 8920, according to the table the memory is installed in the slots with the same color securing clips. I would add that for my XPS 8910, I installed the memory in DIMM1 and DIMM2 (white securing clips) and CPU-Z and HWiNFO64 report dual channel operation. I did not follow the manual but followed the industry practice of using similiar colored securing clips to identify paired slots and also by looking at the XPS 8920 manual for comparison. I think my results proves the XPS 8910 manual, specifically the Table and note, are incorrect. By the way, since the Table and note in the XPS 8920 do not agree, it is also incorrect.

Happy to help, were you able to get the memory working?

Brad,

To answer your question, yes, on the board the DIMM slots are labeled XMM2, XMM4, XMM1, and XMM3 from top to bottom..The labels are along the left edge of the board. By the way, the memory release tabs are colored in the picture in your link, if black and white are colors.

On yours do the colors alternate like the picture or are there two black (together) and then two white (together)? And if it is the same as the picture, is your memory installed in the slots labeled XMM2 and XMM1 (so numbers 25 and 27 per the board layout image)? Sorry for all of the questions, I am just curious.

Thanks for the discussion on this,

Brad

The colors alternate just like the picture. My memory is installed in XMM1 and XMM2. I hope this discussion helps all those with XPS 8910 or XPS 8920 who want to install memory because the manual is confusing. By the way, I think I mentioned this earlier, I think the memory configuration matrix does not list all the possible memory configurations; it did not list the one my XPS 8910 came with which was a single 16 GB memory module installed in XMM1 operating in single channel mode.

Thanks so much for confirming this. I think this topic will help as well just in case someone has issues/questions with installing the memory.

Best regards,

Brad