Sandia National Labs were at a career fair at my university. When I talked to them, they seemed to focus mostly on my GPA before offering me an on-campus interview later in the week. I was interviewed by two people, and both took notes on what looked to be a company form based on what I could see. At the interview I was informed that they are not slot hiring for a specific position, but that if I applied online for any positions, having this interview would give me an advantage over other applicants. If I am contacted about any positions I apply for, the procedure will be an onsite interview, including a seminar on my thesis research.