It's not really a "Dual GTX 580", its just 2 GF110 GPU's on one PCB. Due to the low clock speeds the Performance is closer to 2 GTX 570's in SLI. I would stay away from this card, especially for FFXIV. A single GTX580 is still the better choice in my opinion as dual GPU cards have more disadvantages than benefits (Heat, Noise, poor OC potential, no option for 3rd pt cooling etc.).

Great review by Anand:
http://www.anandtech.com/show/4239/n...ngle-card-king