The Xbox One’s disk drive has been designed to work horizontally, and gamers who put their Xbox Ones vertically do so “at their own risk,” according to senior director of Xbox product management Albert Panello.
While the Xbox 360 was able to work while set flat or up on its side, the Xbox One has no vertical capabilities, rendering it unable to tower above your other consoles like an imposing monolith. Not only will it not work while vertical, it may even damage either your games or the console itself. Later iterations of the Xbox One may change this, but early adopters should stick with orienting their Xbox Ones on the x-axis.