$300-$375 gaming pc with OS

Solution
That's an amazingly tall order - that's essentially a $275 PC since you need an OS.

PCPartPicker part list / Price breakdown by merchant

CPU: AMD A8-5500 3.2GHz Quad-Core Processor ($88.99 @ SuperBiiz)
Motherboard: MSI A55M-E33 Micro ATX FM2+ Motherboard ($39.99 @ Newegg)
Memory: Crucial 4GB (2 x 2GB) DDR3-1600 Memory ($44.99 @ Amazon)
Storage: Western Digital Caviar Blue 320GB 3.5" 7200RPM Internal Hard Drive ($33.49 @ Amazon)
Case: Fractal Design Core 1000 USB 3.0 MicroATX Mid Tower Case ($24.99 @ NCIX US)
Power Supply: Antec Basiq 350W ATX Power Supply ($29.98 @ OutletPC)
Optical Drive: Samsung SH-224DB/BEBE...

DSzymborski

Curmudgeon Pursuivant
Moderator
That's an amazingly tall order - that's essentially a $275 PC since you need an OS.

PCPartPicker part list / Price breakdown by merchant

CPU: AMD A8-5500 3.2GHz Quad-Core Processor ($88.99 @ SuperBiiz)
Motherboard: MSI A55M-E33 Micro ATX FM2+ Motherboard ($39.99 @ Newegg)
Memory: Crucial 4GB (2 x 2GB) DDR3-1600 Memory ($44.99 @ Amazon)
Storage: Western Digital Caviar Blue 320GB 3.5" 7200RPM Internal Hard Drive ($33.49 @ Amazon)
Case: Fractal Design Core 1000 USB 3.0 MicroATX Mid Tower Case ($24.99 @ NCIX US)
Power Supply: Antec Basiq 350W ATX Power Supply ($29.98 @ OutletPC)
Optical Drive: Samsung SH-224DB/BEBE DVD/CD Writer ($14.99 @ Newegg)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($84.99 @ NCIX US)
Total: $362.41
Prices include shipping, taxes, and discounts when available

You're not going to do much better in this price category and this is not a PC I'd recommend buying. You may do better finding an inexpensive outlet PC, though that's going to be very weak as well.
 
Solution

Iron124

Reputable
Jun 1, 2014
607
0
5,360
About the tightest budget ever, but I did it.

PCPartPicker part list / Price breakdown by merchant

CPU: AMD Athlon X2 370K 4.2GHz Dual-Core Processor ($55.73 @ OutletPC)
Motherboard: Gigabyte GA-F2A55M-S1 Micro ATX FM2+ Motherboard ($34.69 @ Newegg)
Memory: Team 4GB (1 x 4GB) DDR3-1600 Memory ($35.98 @ OutletPC)
Memory: Crucial 2GB (1 x 2GB) DDR3-1600 Memory ($23.23 @ Amazon)
Storage: Western Digital Caviar Blue 320GB 3.5" 7200RPM Internal Hard Drive ($33.49 @ Amazon)
Video Card: XFX Radeon R7 250 2GB Core Edition Video Card ($62.98 @ SuperBiiz)
Case: Rosewill FBM-01 MicroATX Mini Tower Case ($23.98 @ Newegg)
Power Supply: EVGA 430W 80+ Certified ATX Power Supply ($19.99 @ Newegg)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($84.99 @ NCIX US)
Total: $375.06
Prices include shipping, taxes, and discounts when available

Will play most modern titles on medium anyway.