I see you read about the CPU for gaming. I'll copy it again here.
"Our tests demonstrate fairly little difference between a $225 LGA 1155 Core i5-2500K and a $1000 LGA 2011 Core i7-3960X, even when three-way graphics card configurations are involved. It turns out that memory bandwidth and PCIe throughput don't hold back the performance of existing Sandy Bridge-based machines. "
The video card might be changed. I'd see how high I can go on this list.
The PSU is something of a problem area. Is it a single rail? If not are you sure you won't exceed the Amperes of any rail? Part of the reason of getting a single rail is for folk that don't want to learn about this.
I am looking on eBay at a ready assembled desktop PC in a couple of different configurations all of which are designed around gaming. I have a budget limit of $1050 and have run into a few questions regarding motherboard and case. I will supply my own operating system, keyboard, mouse and screen. The general build goes as follows:
CPU - Ivy Bridge Intel i5 3570k
RAM - 8gb DDR3 1333MHz
HDD - 1gb SATA III Hard Drive
Motherboard - B75M Pro OR for $50 more 4th Gen Z77 Pro
DVDRW - Generic
Case - Generic with 2 USB ports at the front OR Thermaltake V3 for $30 or V4 for $55
GPU - 1G GTX 660
Power supply - Generic 850W
Here is the link - http://tinyurl.com/au4yacq