This is the setting that controls vertical synchronization (vsync). I've been running Fallout 4 with iPresentInterval=1. I like having my games run at 60 FPS, but I also don't like using Vsync as it causes mouse lag, which can be a huge detriment when playing a game that requires you to have a steady aim at a target.
So this is a problem I've been encountering specifically with Bethesda games, as they have this odd tendency to act odd when you push past a certain framerate.
