If you disable scaling, then 1440p can be shown with letter boxes all around at native 1:1 sharpness. However this is useful only on a large (32 inch +) monitor that is placeed a bit too close.
For eg: If showing 1080p without scaling on a 32" 1440p monitor, it will be the same size as a 24" inch monior.
Black = full 4k area. White = 1440p unscaled content
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The advantage here is that the apparent FOV reduces, so that I don't need to put too much effort to look at the sides/corners to check HUD/chat while playing fast paced FPS games.
This way you get a big desktop with lot of screen area for multi-tasking and you can trade in that resolution for higher fps while gaming.