One PCI Express* 2.0 x 16 bus add-in card connector
Two PCI Express 2.0 x 1 connectors
One PCI Conventional bus connectorhttp://www.intel.com/content/www/us/en/motherboards/desktop-motherboards/desktop-board-dh55pj.html
So basically the limit here is PCI-E-2.0, and the power supply. You're probably not going to be able to put a lot of power through the video card unless you upgrade your power supply. I recommend either A: You get a TI PCI-E Card from nvidia, or B: Upgrade your power supply to get a better video card. Probably the best card you can get is a 660 TI.