The CPU while dated isn't the bottleneck here.

""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 "

So while I wonder why the 4GB video card over say a 290, you can easily find benchmarks for games on the 270.

Be sure to keep it clean (canned air) and replace that heat sink compound. Why? Example at:
http://www.tomshardware.com/reviews/radeon-r9-290x-thermal-paste-efficiency,3678-3.html

Bob