pcie 3

I have a WX58BP Intel motherboard which has two PCIe 2.0 x16 slots, and I already have a nVidia EVGA GTX 465 card. Now since my 3D software is asking for more, I want to add another graphics card. I am looking for options like nVidia ASUS GTX 570 or GTX 680, because I want to make use of...