Going to buy an XPS 8700. Can anyone tell me what outputs the nvidia gtx 635 & 645 have? Dual monitor support? PCI express 3.0 x16?

  I'm looking at buying an xps 8700, and am bouncing between the package with the nvidia 635 & 645 video cards.  I'm also looking to get new monitors as well.  I want to make sure what outputs each video cards have, do either support dual monitors, and if I have to upgrade the vid card does the mobo support PCI express 3.0?  I want make sure before I make the purchase.  If anyone can tell me these things I'd be very appreciative.

these are the two models I'm looking to buy, if that helps at all.  Dual monitors is a must for my video/grahpic design.  Ideally I'd want 1 DVI and 1 HDMI.  If one or the other HAS to be for the primary display I'd like to know that as well so I can make sure to purchase the correct input for my bigger/nicer monitor.

http://www.dell.com/us/p/xps-8700/pd?oc=fdcwgx312&model_id=xps-8700

http://www.dell.com/us/p/xps-8700/pd?oc=fdcwgx315&model_id=xps-8700

Thanks a heap