That will play most games on Ultra. You don't want a 3x RAM kit though, you want either 2x4GB or, perhaps for future resistance, 2x8GB.
You may wish to add a 120mm tower-style cooler, especially if you intend to overclock. I recommend the Xigmatek Gaia. Per Frostytech reviews, it cools within 1C of the more commonly mentioned Hyper212 EVO, but is quieter, and $10 cheaper (in the US; your prices should be similar).
Don't forget an optical drive, if only to load Windows and those applications and games not available online.