ASUS Mars II 3 GB Dual GTX 580
 

The ASUS MARS II is a monster graphics card consisting of two GeForce GTX 580 GPUs on a single PCB using triple slot cooling. Unlike the NVIDIA GTX 590, the MARS II comes with full GTX 580 clock speeds which give the card an almost 20% performance advantage over the GTX 590, making the card the fastest graphics card in the world, but also the most expensive at $1500.

http://www.techpowerup.com/reviews/ASUS/Mars_II/