There are 2 rounds of phone interviews. The first round is to talk with the project manager and it's been hard-core. The first question they ask is "TCP and UDP" which is very weird LoL. Then I was asked to code on collabedit and asked a lot of optimization questions. I am not a CS student so they appear to be very difficult. I was also asked to write a method for doubly linked list which is not hard. But I was asked again about optimization issue which I stuck. Overall the first round is quite hard. The second round is talking with a group leader. There are technical questions about computer architecture, and I am quite familiar with the topic so we have a nice talk. He also asked about the projects I have done and what optimization I could do to future CPU. It's been the area which I am working on so I have had a nice time talking. I was having a pending offer from Oracle so I asked NVIDIA to give me a quick reply. I received a confirm of offer 1 day after the interview which is amazing.

multiple phone interviews followed by an on site interview, hr seemed rather slow with multiple weeks between contact for scheduling the next interview