Yeah it's a built in system. You'd check nVidia Control panel to see if there is a setting, but that happens on every card I know of - my 6950s do it. There is no point in changing it though, it saves power and I don't think there would be any difference should you be able to disable that. Why would you want to get rid of it anyway?
It could, on the other hand, be something to do with Asus motherboards, because I've only ever gone with Asus.