I have an interview for a PhD studentship, but I'm not sure what to wear.
I want to impress, but not be overdressed.
I am male.

Any advice is appreciated.

I wore a suit to mine. I think it shows you're taking the interview seriously and also gives you an air of authority when presenting etc. Much better to be over dressed than under dressed

It depends on the culture as well. In my opinion, it may not look nice if you are wearing a suit and your examiners are not. Just a thought :)

I agree with bunker that it depends on the culture, but if you don't have that kind of information, I would say that if in doubt, wear a suit. It shows that you're serious about the job and want to make a good impression. It's much better to risk being more smartly-dressed than your interviewers than the other way around.

A suit is good but, some people are not comfortable in a suit. I personally think that smart and comfortable is best.
It does depend on the culture, as others have suggested.

Just wear a formal dress because there is no rule for any interview that you must wear the professional dress which they decide.

I think you will find you are overdressed if you wear a suit.

Probably depends on the field though. Biology is very casual.