So, I'm in the market for building a new rig for gaming. The problem is I can't decide on a graphics card. My budget is around $500 and I am definitely going with ASUS, my question is since I am putting a Xonar D2X sound card in I only have 3 pci-e slots left open; I decided I was either going to put in two Direct CU II ENGTX 560 TI 1 GB DDR5 or one Direct CU II ENGTX 580 1536 MB DDR5. Which one should I purchase or is there a better configuration for my new rig. My current specs are: Corsair AX1200 W psu, 12 gb of 2000 mhz corsair dominator gt ddr3, asus rampage iii extreme motherboard, asus xonar d2x sound card, core i7 960 3.2 ghz processor, and I'll be putting these in a thermaltake level 10 gt case.