I think this guy I know is trying too hard.
Is he trying to impress someone?
He just talks about what he's fascinated with at that moment
It can be hard to make small talk. It's not right to say he's trying too hard when you don't really know how you would do if they shoe were on the other foot. Do what you can to add to the conversation, and he might relax.
I mean, if he really wants to talk, he should just talk.
You shouldn't judge him too harshly on that. It seems like he is just passionate about the things he talks about.