PCPartPicker part list:
http://pcpartpicker.com/p/KbcTgs
Price breakdown by merchant: http://pcpartpicker.com/p/KbcTgs/by_merchant/
CPU: AMD FX-8320 3.5GHz 8-Core Processor ($129.00 @ Amazon)
Motherboard: ASRock 970 EXTREME4 ATX AM3+ Motherboard ($69.98 @ Newegg)
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1866 Memory ($48.99 @ Newegg)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($46.99 @ NCIX US)
Video Card: Sapphire Radeon R9 280 3GB Dual-X Video Card ($149.99 @ Newegg)
Case: Corsair 200R ATX Mid Tower Case ($49.99 @ Micro Center)
Power Supply: EVGA SuperNOVA GS 550W 80+ Gold Certified Fully-Modular ATX Power Supply ($54.99 @ Newegg)
Optical Drive: Samsung SH-224DB/BEBE DVD/CD Writer ($14.98 @ OutletPC)
Operating System: Microsoft Windows 8.1 OEM (64-bit) ($86.98 @ OutletPC)
Monitor: Asus VS238H-P 23.0" Monitor ($139.99 @ NCIX US)
Total: $791.88
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-07-01 23:26 EDT-0400
make sure to check your CPU temps when you get it, if they are too high then you should get an aftermarket cooler
The motherboard supports crossfire in case you want another GPU
The ram is 1866mhz CAS 9 which is better than the one in your build
You may want to consider going down to an fx 6350 and getting an r9 280x