What's the intention here? Replace the existing 1x 8 GB in the XPS 8930 with the 1x 16 GB stick from the XPS 8940? Or use both? What CPU is in the XPS 8930, i3, i5, i7 and what generation, 8th or 9th? The XPS 8940 ships with 3200 MHz RAM but it's not going to run at that speed in the XPS 8930. Depending on which CPU and its generation, the RAM may run at 2666 MHz (or slower). 24 GB is a supported RAM config in the XPS 8930, but Dell only validated 2x 8 GB + 2x 4 GB, and not 1x 8 + 1x 16 GB. And no way to know in advance if the new 1x 16 GB stick will be compatible with the existing 1x 8 GB stick.  Can't hurt to try... Either way, with only one RAM module installed or with a mixed pair, RAM will only run in "single-channel" mode which is slower and less efficient than "dual channel" mode, which requires a matched pair of RAM modules in each bank (slots matching color retention clips).
I recently bought myself a XPS 8940 desktop and along with it 32GB worth of compatible third-party ram sticks . As such, I have no use for the ram stick that came bundled with my desktop ( Hynix HMA82GU6DJR8N-XN, 16GB 2Rx8 PC4 3200AA UB2 11). My father bought an XPS 8930 some time ago with 8GB of RAM and I was intending on giving him said ram stick. I did an overview of the datasheet for the stick as well as for the XPS 8930 and everything seems to be compatible for him to use this ram stick in his system, but I thought it would be wise to consult the community before swapping.  Can anyone confirm whether I'm making a big mistake by doing this? Thank you
Swapping out XPS 8930's ram stick with XPS 8940's