And you apparently found the wrong answer . . . .
Dell XPS 15 (L501X) notebook Memory RAM Upgrade
C'mon guys do we really want to be shooting people down for coming to "our" forum and creating posts and helping our member base grow?
Seriously i don't know the answer the link above suggests 8Gb but i have just read "yes on Google" another forum post that states this CAN take individual 8Gb sticks in each slow so yes 16Gb.
Can i ask why do you want to know, do you just want to know or are you looking at putting 16Gb in, because honestly this would be a complete waste.