In my experience the dress code at academic conferences is really casual. I would just wear what you would normally wear to work, possibly avoiding shorts when giving a presentation (although I have seen plenty of people presenting in shorts). You could also wear a suit, although I think you would be one of the view that does. If you do want to make your clothes a bit more formal for your presentation, I would wear only the jacket of the suit combined with nice shoes, with normal pants and no tie.