$850 Build with Windows and a 23" Monitor

PCPartPicker part list: http://pcpartpicker.com/p/3tkZp
Price breakdown by merchant: http://pcpartpicker.com/p/3tkZp/by_merchant/
Benchmarks: http://pcpartpicker.com/p/3tkZp/benchmarks/

CPU: Intel Core i5-4570 3.2GHz Quad-Core Processor  ($189.99 @ Amazon)
Motherboard: ASRock B85 Pro4 ATX LGA1150 Motherboard  ($64.99 @ Amazon)
Memory: Crucial Ballistix Sport 8GB (2 x 4GB) DDR3-1600 Memory  ($74.99 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive  ($56.98 @ OutletPC)
Video Card: PowerColor Radeon R9 270 2GB Video Card  ($179.99 @ Newegg)
Case: Cougar Solution (Black) ATX Mid Tower Case  ($36.99 @ Mwave)
Power Supply: Corsair Builder 500W 80+ Bronze Certified ATX Power Supply  ($44.99 @ Micro Center)
Operating System: Microsoft Windows 8.1 (OEM) (64-bit)  ($89.98 @ OutletPC)
Monitor: Acer G236HLBbd 60Hz 23.0" Monitor  ($109.99 @ Amazon)
Total: $848.89
(Prices include shipping, taxes, and discounts when available.)

$1100 Bang for the Buck Gaming PC of the Day

PCPartPicker part list: http://pcpartpicker.com/p/3sZjN
Price breakdown by merchant: http://pcpartpicker.com/p/3sZjN/by_merchant/
Benchmarks: http://pcpartpicker.com/p/3sZjN/benchmarks/

CPU: Intel Core i5-4670K 3.4GHz Quad-Core Processor  ($219.99 @ Newegg)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler  ($29.98 @ OutletPC)
Motherboard: MSI Z87-G45 Gaming ATX LGA1150 Motherboard  ($119.99 @ Newegg)
Memory: G.Skill Ares Series 8GB (2 x 4GB) DDR3-1600 Memory  ($64.99 @ Newegg)
Storage: Samsung 840 EVO 250GB 2.5" Solid State Disk  ($151.95 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive  ($56.98 @ OutletPC)
Video Card: PNY GeForce GTX 770 2GB Video Card  ($310.49 @ Amazon)
Case: Corsair 200R ATX Mid Tower Case  ($49.99 @ Newegg)
Power Supply: Corsair CX 600W 80+ Bronze Certified Semi-Modular ATX Power Supply  ($67.13 @ Amazon)
Total: $1071.49
(Prices include shipping, taxes, and discounts when available.)