I reached NVIDIA on a campus career fair. The recruiters were straightforward, they gave candidates a quiz consists of 4 questions. If the questions are completed correctly, they might give you a phone interview a couple of weeks after. The quiz is about the difficult you may expect from a homework or a midterm from some classes of a junior student in electrical engineering. I remember one question is asking you to draw the MOSFETs inside a AND gate. Other questions are from digital circuits. The phone interview is pretty easy, only asked about conceptual questions, no computations involved.

Applied online, got reached out within a week, had two rounds of online interviews then got rejected. Asked standard computer architecture questions and some cache-specific questions. Also asked about interconnect.