Found out the hard way that text won’t display correctly with the Dell U2711 panel if you’re using DVI and you try to re-use your existing cable.  It comes with a cable marked “DVI Dual”.  Better make sure to use it.

Also worth noting: your GPU must also support DVI-D.

Reference: http://en.community.dell.com/support-forums/desktop/f/3515/t/19339634.aspx answer by “xprt"