The Player's Handbook says that Drow can use magic, which allows them to cast the cantrip Dancing Lights, as well as cast Faerie Fire at level three and Darkness at level five. It says that Charisma is your spell casting ability for these spells.
If you want to be a wizard it says that Intelligence is your spell casting ability. What happens in the place of a Drow wizard? Is it still Charisma for the first three and Intelligence for all the others of do you use one ability for all of them? I'd like to know which ability to give a higher score to.