what resolution and what games? what are your other system specs? If a higher resolution, keep in mind you may need more than the options given, where the 660 would probably be weaker due to lack of memory bandwidth. For higher resolutions, the 670 or 7950 would be a better solution.
If you are at a moderate resolution, such as 1920x1080 or 1920x1200, the mentioned should be fine, depending on the games and settings.
5930k @ 4.2 GHz under CM Hyper 212 Evo
R9 290 crossfire 2x Sapphire Tri X | Seasonic 1250 Gold
16GB Corsair Vengeance LP on Asus X99 Deluxe
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950 Pro 512 GB + 850 EVO 500 GB + 2TB WD Black