HELP!

2xGTX660ti>GTX680


2xGTX660ti<2xGTX670. However, depending on the rest of the PC specs, games, resolutions and image settings, their difference can either be either quite significant or minimal.

heres the specs

PCPartPicker part list: http://pcpartpicker.com/p/AgKu

CPU: Intel Core i7-3930K 3.2GHz 6-Core Processor
CPU Cooler: Noctua NH-D14 SE2011 CPU Cooler
Motherboard: Asus Rampage IV Extreme EATX LGA2011 Motherboard
Memory: Corsair 16GB (2 x 8GB) DDR3-1600 Memory
Memory: Corsair 16GB (2 x 8GB) DDR3-1600 Memory
Memory: Corsair 16GB (2 x 8GB) DDR3-1600 Memory
Memory: Corsair 16GB (2 x 8GB) DDR3-1600 Memory
Storage: Seagate Barracuda 2TB 3.5" 7200RPM Internal Hard Drive
Storage: Kingston SSDNow V200 Series 64GB 2.5" Solid State Disk (raid0)
Storage: Kingston SSDNow V200 Series 64GB 2.5" Solid State Disk (raid0)
Video Card: Galaxy GeForce GTX 660 Ti 3GB Video Card (2-Way SLI)
Video Card: Galaxy GeForce GTX 660 Ti 3GB Video Card (2-Way SLI)
Case: NZXT Phantom (Black) ATX Full Tower Case
Power Supply: XFX ProSeries 850W 80 PLUS Silver Certified ATX12V / EPS12V Power Supply
Optical Drive: Lite-On iHAS124-04 DVD/CD Writer
Operating System: Microsoft Windows 8 Full (64-bit)