XPS 8900, U2414H, NVIDIA(R) GeForce(R) GT 730 2GB DDR3 Connect 2 monitors to the PC - Best Options

The U2414H monitor has HDMI and DisplayPort (DP) inputs, and that video card seems* to have DVI-D, HDMI and VGA outputs

Your first monitor can be connected HDMI (add-in video card)>HDMI (monitor input), keeping in mind the first monitor has to be connected to the add-in video card, not to the onboard HDMI video port on the PC.

For the second monitor, you could use a DVI-D (add-in video card output)>HDMI (monitor input) cable since that video card appears to support 2 monitors.. 

Alternatively, the second monitor could be connected via HDMI (using onboard video)>HDMI (monitor), again keeping in mind the first monitor has to be connected to the add-in card.

Using the onboard HDMI for the second monitor might give you a slightly lower quality signal, but you may or not notice the difference...

*CAVEAT: I am assuming the add-in card has those 3 different outputs so be sure to confirm for yourself before buying any video cables,

EDIT: The DVI-D output on the video card appears to be Dual-Link DVI-D, so assuming that's correct, be sure to get a Dual-Link DVI-D>HDMI adapter cable. These tend to be short, so you may also need a longer HDMI>HDMI cable to go from the "adapter" to the monitor.

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