Good looking system but I would double the ram to 2 x 4gb Sticks. It will cost you very little extra and future proof against higher spec games and allow video editing etc.
Your power supply should be upped a little to accomodate overclocking your current psu will be stressed. A CX600 would be much more suited to yourself imo.
You have chosen a SB chip, not Ivy bridge. If you want true PCI3 you need a Ivy bridge i5 3570k