I would step Down the i5-3570k to a i5-3570 (non-k version) and a B75 MOBO. You haven't choosen any decent CPU cooler, so no reason to get an overclockable CPU and MOBO.
The B75 mobo could be this http://www.techpowerup.com/reviews/Gigabyte/B75M-D3H/13.html
By the Money you save upon going Down on the MOBO and CPU you could upgrade to 2x4 GB RAM and a GTX 660 or a Radeon 7870.
That would prove to give you the best performance.