Quad HD is 2560x1440? No... it's not. Not one bit. Quad is HD is exactly four full HD quadrants, or 3840x2160. And the "full HD" descriptor exists because 1280x720 (720p) is referred to as "HD." And 1920x1080 is also referred to as "HD," so they added in the "Full" to make it more clear.
I don't understand why…