CPU: Intel Core i5-3570K------------------------------------------------------------------------$189.99
http://www.microcenter.com/product/388577/Core_i5_3570K_34GHz_LGA_1155_Processor
Reasoning: Great processor for gaming, built by a reliable company! Also, if you go with Microcenter, you get a $40 off Mobo/CPU bundle!
GPU: Gigabyte Radeon HD 7970 GHz Edition--------------------------------------------------$399.99
Reasoning: Can run almost any game you throw at it on maxed out settings with smooth FPS!
You also receive Crysis 3 & Bioshock Infinite for free!
Memory (RAM): Corsair Vengeance 8 GB 1600mHz DDR3 RAM----------------------------$51.99
http://www.amazon.com/Corsair-Vengeance-PC3-12800-1600mHz-CMZ8GX3M2A1600C9B/dp/B004QBUL1C
Reasoning: No need for more than 8 GB RAM for gaming, and Corsair is a great brand!
CPU Cooler: Cooler Master Hyper 212 EVO----------------------------------------------------$32.99
http://www.amazon.com/Cooler-Master-Hyper-212-RR-212E-20PK-R2/dp/B005O65JXI
Reasoning: Great cooler, unless you're doing any serious overclock, it will do just fine!
Storage: Western Digital Green TB 3.5" 7200RPM 1.5 TB HDD-------------------------------$84.99
http://www.amazon.com/Green-1-5-Desktop-Hard-Drive/dp/B004VFJ8J4
Reasoning: Plenty of space for gaming and WD makes a great product!
Power Supply: Corsair TX650M-------------------------------------------------------------------$89.99
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139031
Reasoning: Good, reliable company, and 650 Watts is plenty!!
Motherboard: MSI Z77A-GD65-------------------------------------------------------------------$159.99
http://microcenter.com/product/401766/Z77A-GD65_Socket_LGA_1155_ATX_Motherboard
Reasoning: Good Motherboard with a clean BIOS, great for overclocking. Also, if you go with Microcenter, you get a $40 off Mobo/CPU bundle!
Case: CM Storm Stryker----------------------------------------------------------------------------$169.99
http://microcenter.com/product/402314/Storm_Stryker_Gaming_Full_Tower_Computer_Case_with_Carrying_Handle_-_Black-White
Reasoning: Very nice case. Plenty of room for airflow and all of your components. Great cable management, window on the side, plenty of places for additional fans. Worth the money imo!
Optical Drive: Any cheap optical drive will do!
Reasoning: I'm using an external one because all of my drive bays are used up, but you can buy any cheap one to throw in your case for $10-$20.
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit)------------------$99.99
Reasoning: Memory limit of 16 GB, but you don't need that much or any more than 8 GB for gaming.
Total cost =
$1,279.91
Now you can always make this cheaper by downgrading the case, maybe grab a 7870 or 7950 GPU, maybe get 2 gigs less of ram, but this is a very solid gaming rig IMO, and you can also add lots of fans because it is such a nice case!
If you have any questions feel free to ask, and make sure to tell me if I missed anything!