When I first got these nice looking LG Ultrawide displays here at work I spent a considerable amount of time getting the resolutions right. All in all I wound up having to use SwitchResX to get them to work properly. That was a while ago and I forgot the torment I went through to get it right.
Well, with the latest update to Sierra, I got a pleasant reminder. So, here you are, the SwitchResX settings I finally got to work with these puppies.