Backlight variance (bleed)
We do not validate our monitors in a dark room. We validate our monitors in rooms with a minimum of 150 lux which is standard office lighting. Dell monitors do not have 100% backlight uniformity specification. As long as the center 4" circle (7" circle for 27" and larger monitors) meets our manufacturer specifications, it is acceptable.
Color/Tint variance
Dell monitors do not have 100% color/tint uniformity specification. As long as the center 4" circle (7" circle for 27" and larger monitors) is 6500K, it meets our manufacturer specifications. The center may be 6500K, but the sides and corners may not, which is why you may see that one side or corner is different than the others. To obtain closer color temperatures, use Custom Color in the monitor OSD (On Screen Display) to adjust the RGB to match up the monitors.