Here's what I recommend you :
PCPartPicker part list:
http://pcpartpicker.com/p/1Doxr
Price breakdown by merchant: http://pcpartpicker.com/p/1Doxr/by_merchant/
Benchmarks: http://pcpartpicker.com/p/1Doxr/benchmarks/
CPU: Intel Core i5-4670 3.4GHz Quad-Core Processor ($208.98 @ SuperBiiz)
Motherboard: MSI B85-G41 PC Mate ATX LGA1150 Motherboard ($78.23 @ Outlet PC)
Memory: G.Skill Ares Series 8GB (2 x 4GB) DDR3-1600 Memory ($57.99 @ Newegg)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($59.99 @ NCIX US)
Video Card: Asus GeForce GTX 670 2GB Video Card ($247.55 @ Newegg)
Case: Corsair 300R ATX Mid Tower Case ($59.99 @ Microcenter)
Power Supply: XFX 550W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply ($44.99 @ NCIX US)
Optical Drive: Samsung SH-118BB DVD/CD Drive ($13.99 @ Newegg)
Total: $771.71
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-09-13 18:25 EDT-0400)