recent user complaints are if bios is updated you would not be able to use 2x16 GB that used to boot in this model on previous bios.  you would have to use one of the Dell stock ram (8 or 4 gb) along w new ram to boot.  so beware do not update bios if you can help it. Dell spec says  ● 4 GB, 1 x 4 GB, DDR4, 2666 MHz, 2933 MHz● 8 GB, 1 x 8 GB, DDR4, 2666 MHz, 2933 MHz● 8 GB, 2 x 4 GB, dual-channel, DDR4, 2666 MHz, 2933MHz● 12 GB, 1 x 4 GB + 1 x 8 GB, DDR4, 2666 MHz, 2933 MHz● 16 GB, 1 x 16 GB, DDR4, 2666 MHz, 2933 MHz● 16 GB, 2 x 8 GB, dual-channel, DDR4, 2666 MHz, 2933MHz● 32 GB, 1 x 32 GB, DDR4, 2666 MHz, 2933 MHz● 32 GB, 2 x 16 GB, dual-channel, DDR4, 2666 MHz, 2933MHz● 64 GB, 2 x 32 GB, dual-channel, DDR4, 2666 MHz, 2933MHz 2933 MHz, 2666 MHzNOTE: 2933 MHz speed memory modules are onlyavailable for computers that are shipped with 11thGeneration Intel Core i5/i5F/i7/i7F processors. this means the same ram runs at two different speed depending on your cpu.  for 10th the bios will make ram run at 2666, for 11th at 2933.  even though your ram spec says 2933, when it is used with your 10th gen cpu, it will be downclocked to 2666.  Dell does not sell two different ram in this model.  it is the same ram whether cpu is 10th or 11th.  but this ram can go up to full speed of 2933 only with 11th gen cpu.  
Hello, I recently purchased a Dell Inspiron 3891. It came with 12 GB RAM - 1 8 GB stick + 1 4 GB stick. I was wanting to upgrade the 4 GB to another 8 GB to get the total RAM to 16 GB, but something has confused me that I need help with. My 3891 has an Intel 10th Generation Core i7 10700 processor (8-Core, 16M Cache, 2.9GHz to 4.8GHz). Looking for the right kind of RAM memory, I read this here: [URL] "NOTE 2933 MHz speed memory modules are only available for computers that are shipped with 11th Generation Intel Core i5/i5F/i7/i7F processors." But according to my invoice, my 3891 came with "12GB, 8Gx1 + 4Gx1, DDR4, 2933MHz". So, apparently Dell shipped to me a 10th Gen Intel PC with 2933 MHz RAM that Dell says should only be used with 11th Gen Intel CPUs. So which is correct here? I need to know so I get the proper RAM upgrades for my PC. Any feedback here would be great!
Dell Inspiron 3891 RAM Upgrade Question