The LCD Moniter only understands digital information not analog. So if you use a non-DVI connection your videocard is changing digital information into analog and then the monitor needs to change it back to digital again. Due to the nature of analog the conversion is never perfect, information is misinterprited and the image you get is poor. Using DVI the information is never converted into analog. This protects integrety of the data and you get an excellent image using DVI.