I just purchased a XPS 8940 (11th gen i7 processor) that came with 16GB RAM (2 8GB sticks). Since I do photo editing that can sometimes be intense, I wanted to add more ram, so I ordered 2 of these, that were the recommended memory sticks from Dell: 16GB - 1RX8 DDR4 UDIMM 3200MHz. This would give me 48GB ram, which is plenty for what I need to do.
I added the additional memory to the open slots on the MB (in this case, the black slots), leaving the original 16GB on board. When I add the additional memory, the computer will not boot.
If I remove the original memory and put just the new sticks in their place (the white slots), it will not boot.
If I leave the original memory in, and just add one of the new sticks, it will not boot. I switched out the new sticks, and swapped which slot they were in. Nothing.
If I take out the original memory and move them to the black slots, it will not boot. My guess is that something has to be in the white memory slots.
The only thing I can think of is that the memory selector is wrong, or (as unlikely as it must seem), both new memory sticks are bad.
When the new memory is installed, I don't even get the Dell logo so I can access the BIOS.
I'll try to give Dell a call on Monday, but in the meantime, I'll accept any suggestions.
It's always a good idea to clear BIOS by removing the motherboard battery and pressing/holding the power button for ~30 sec after making a major hardware change, eg, installing additional RAM or moving the modules into different slots. That forces BIOS to see the changes...
No guarantee clearing BIOS will allow 48 GB to work because the two pairs may just not be compatible with each other, regardless of slots.