Ok I took a look at the manual (chapter 4
http://www.hisdigital.com/UserFiles/...0_6870_ENU.pdf) and with the 6000 series cards you can only use 1 of the 2 DVI slots at once. So you have 1 monitor through DVI port, 2nd through HDMI and for monitor 3 you need a active display port to dvi adapter. NCIX or similar sells em.