Effects of streaming at more fps than the game runs at

I've got so much to learn about stream settings, but for now I was wondering if I were to have OBS set to 45fps, what would that do to a game running at 30fps.
For example, if I were to use the Elgato Game Capture HD to capture at 720p, 60fps allowed, capturing Alien: Isolation on the Xbox 360, but had OBS set to 45fps, would it look worse than if I had OBS set to 30fps? How does this work?
Sorry techies on here, I'm sure this is the noobiest question to you guys! XD

Submitted by PumpkinMilkshake Xbox 720 Release Date 2015