10-bit color, aka "Deep Color" is a scheme where 10 bits are used for each color channel. This makes for a 30 bit RGB implementation.
IE: red: 10 bits green: 10 bits blue: 10 bits total: 30 bits
For more information, please consult this link http://en.wikipedia.org/wiki/RGB_color_model#Beyond_truecolor:_deep_color
Radeon 6000 series cards DO support deep color over HDMI, but HDMI also limits the output resolution to 1920x1200, which is not optimal. I want to know if Deep color is possible over display port with the HD6xxx series graphics cards.