You just installed OBS and connect to your shiny new Logitech C920 to realize that the frame rate is garbage. This article will explain to you how to solve that issue.
Too long didn’t read
Simply select the video format of “YV12 (emulated)” to get the promised 30fps at full HD resolution.
To the best of my knowledge, this issue comes from the fact the YV12 is a 4:2:0 sampling in opposite to a regular YUV which would be a 4:2:2 sampling with OBS. That switch from 4:2:2 to 4:2:0 seams to free enough bandwidth to allow for the promised 30fps.
More info about sampling can be found here.