need graphics card

Solution
Depends what are you planing to play. Here i made some changes.

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: AMD FX-6300 3.5GHz 6-Core Processor ($109.99 @ Amazon)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler ($29.98 @ OutletPC)
Motherboard: Asus M5A97 R2.0 ATX AM3+ Motherboard ($94.99 @ Amazon)
Memory: G.Skill Ares Series 8GB (2 x 4GB) DDR3-1866 Memory ($68.85 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($58.99 @ NCIX US)
Video Card: MSI Radeon HD 7870 GHz Edition 2GB Video Card ($129.99 @ Newegg)
Case:...
Depends what are you planing to play. Here i made some changes.

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: AMD FX-6300 3.5GHz 6-Core Processor ($109.99 @ Amazon)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler ($29.98 @ OutletPC)
Motherboard: Asus M5A97 R2.0 ATX AM3+ Motherboard ($94.99 @ Amazon)
Memory: G.Skill Ares Series 8GB (2 x 4GB) DDR3-1866 Memory ($68.85 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($58.99 @ NCIX US)
Video Card: MSI Radeon HD 7870 GHz Edition 2GB Video Card ($129.99 @ Newegg)
Case: Antec One ATX Mid Tower Case ($29.99 @ Newegg)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply ($25.99 @ Newegg)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($82.99 @ NCIX US)
Other: Microsoft Office Home and Student 2013 (1PC/1User) [Download] ($113.40)
Total: $745.16
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-11-23 10:14 EST-0500)
 
Solution