We're excited to announce that we've fully migrated the Xbox Forums to their new home, here on the Microsoft Community forums!
As of today, going to forums.xbox.com will redirect you here to the Xbox area of the Community forums. We've moved all of your existing threads over so you can continue and start conversations with the new forums experience.
We sincerely appreciate the feedback you have provided over this transition and can't wait for you to check out the new Xbox Forums!
The Xbox One S is able to upscale 720p/1080p to 4K. There is currently no setting for 1440p yet.
As Wichrun X has shown, 1440p support is coming soon. It is apparently making its rounds in the early Preview ring for testing, and will be arriving to public system updates in the coming months. How long, exactly? Nobody knows just yet.