The Crucial Ram you show are the SAME. They will operate as Single Rank when paired with another 16GB that is Single Rank, like the Dell RAM you have. Get 2 of those and use them, it will be run as Dual Rank. The difference between the 2, the first you get 2 'random' sticks, the 2nd is a matched pair of sticks from the same batch. Generally that is what is 'guaranteed' to work together. I was sort of lucky, in that I wound up with 2 with the same Week/Year date. That doesn't ensure I have the same batch/wafer chips on the stick though. So far in the six months they've been installed, I've had no problems that I could say were RAM problems. If you wanted to stay Single Rank (and from my testing, I can't say that would be a noticeable lag that you could tell) buy only one stick and go to 32GB that way. Have a problem with the mix of makers of the RAM sticks, buy another 16GB from Crucial then. Like I said, I had used the Dell and Crucial sticks together for 3 weeks without a problem. Some good reading on this, [URL] but as long as you match the spec's, Speed, voltage, latency, etc. is probably wouldn't matter. Even is speed were different, you'd only run at the slowest speed, and even then, no sure you'd notice any degradation in operation? Also [URL] I also used the 2 sticks in the same channel 1 (8940 is color coded for channels) and different channels with each in Slot 1 for the channel, that would be the 2 White slots and different changes, slot 5 and 6. [IMAGE]   CL21 is the lower speed 2933 RAM I recall? Even if you put that, or the 2666 speed CL19 in, it will still work, just slower, and again, you might never notice it. RAM speed is a small part of the overall action of a PC operation. Many more are done by the CPU usually.
I am wondering what Rank 1 vs Rank 2 RAM means?   [URL] I have a XPS 8940 with i7 11700 with 1 16GB RAM DIMM Which one do I add to the system 1. Dell Memory Upgrade - 16GB - 2Rx8 DDR4 UDIMM 3200MHz or 2. Dell Memory Upgrade - 16GB - 1RX8 DDR4 UDIMM 3200MHz
XPS 8940, RAM upgrade, Rank 1 vs Rank 2?