I rarely find duals to be a good move. Most folk blow up at the need for a new big PSU or falter at the rails discussion.

We know the CPU is fine. Here's a prior quote.
"Our tests demonstrate fairly little difference between a $225 LGA 1155 Core i5-2500K and a $1000 LGA 2011 Core i7-3960X, even when three-way graphics card configurations are involved. It turns out that memory bandwidth and PCIe throughput don't hold back the performance of existing Sandy Bridge-based machines. "
http://www.tomshardware.com/reviews/gaming-cpu-review-overclock,3106-4.html
..