600$ budget for gaming computer

No a lot of money left for keyboard
USB 3 case +mb
7850 2GB

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: AMD Phenom II X4 965 Black 3.4GHz Quad-Core Processor ($89.99 @ NCIX US)
Motherboard: Gigabyte GA-78LMT-USB3 Micro ATX AM3+ Motherboard ($49.99 @ Microcenter)
Memory: Kingston HyperX Grey 8GB (2 x 4GB) DDR3-1600 Memory ($47.98 @ Amazon)
Storage: Seagate Barracuda 500GB 3.5" 7200RPM Internal Hard Drive ($56.98 @ Outlet PC)
Video Card: XFX Radeon HD 7850 2GB Video Card ($179.99 @ Newegg)
Case: Cooler Master Elite 431 Plus (Black) ATX Mid Tower Case ($39.99 @ Amazon)
Power Supply: Corsair Builder 430W 80 PLUS Bronze Certified ATX12V Power Supply ($19.99 @ Newegg)
Optical Drive: Samsung SH-224BB DVD/CD Writer ($15.98 @ Outlet PC)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($89.98 @ Outlet PC)
Keyboard: Rosewill RK-200 Wired Standard Keyboard ($6.99 @ Amazon)
Total: $597.86
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-03-22 03:09 EDT-0400)