CPUID says I have ONE 16GB PC2133 memory running single channel
Looking to install TWO 8GB memory ( dual channel )
Memory selector says crucial CT8G4DFS824A
I would guess that if the 2 x 8 GB RAM modules were not in stock then 1 x 16 GB was picked instead...but that is a huge guess and I agree that 2 x 8 is required for dual channel operation. I believe that Crucial RAM you posted is the same as the specified RAM here.
And FYI, I have seen new systems with an M.2 NVMe/'PCIe SSD and a hard drive and yet the OS is installed on the HDD and not the SSD so go figure.
You are right, it is lame. Many have complained over the years. Dell has been listening (at least for high performance machines) and DIMM-count is sometimes specified now on sales-config-page .
However, what is done-is-done . I would not waste money swapping 16gb for 8+8gb on this older machine.
Dual-channel is faster, but only slightly. Plus, you would have to be really using machine hard to realize any perceivable gains.
My XPS 8910 also came with one 16GB memory module and am happy it did because I only had to buy another 16GB memory module from crucial.com to have 32GB total memory. As an added benefit it now runs in dual channel mode. If it came with two 8GB modules I would had to buy two more 8GB modules and use up all the memory slots. Now I still have two free memory slots.
Also note that the original configuration (one 16GB module) and the current configuration (two 16GB modules) are not listed in Dell's Memory Configurration Matrix but it works.
Well I just solved my own problem
Best Buy had Corsair DDR4-2400 RAM on sale - why do they sell old slow memory ?
So I replaced the ONE 16GB stick at 2133 for TWO 8GB sticks at 2400mhz
not sure of the MAX speed on the motherboard
Here is my result
I can't see your pictures yet until they are approved, but my experience and what has been reported in this forum is that the Dell BIOS sets the memory speed based upon only the SPD speed. The XPS 8910 does not have the capability to read and use the memory's XMP (Extreme Memory Profile). I have not seen any reports here of memory in the XPS 8910 running faster than 2133 MHz which is the specification for this computer. You can see the memory speed if you go to Task Manager, Performance tab, click on Memory, and look in the lower right.
If you have this Corsair memory, CMK16GX4M2A2400C16, its SPD speed is 2400MHz. It would be interesting to see if the XPS 8910 will actually run at that memory speed.
The pictures I posted show 1200mhz in dual channel mode = 2400
That is with two 8gb ram in the white memory slots
I wonder if the motherboard can handle 2666mhz ?
I don't know if the motherboard can handle 2666 MHz but the Corsair memory I looked at that had a test speed higher than 2400 MHz had a SPD speed of 2133 MHz so that Corsair memory will not run higher than 2133 MHz on that motherboard. Crucial memory may work since some in this forum have used Crucial memory at that speed in the XPS 8930.