Well the first thing is your AMD processor uses Dual Channel memory so you don't want 12 GB. of RAM you want 8 GB., (2 x 4 GB.), as 16GB. is way overkill unless you are doing 3D rendering, Cad, etc.
As far as a mobo is concerned my first choice for quality and performance is always Gigabyte. If you're planning to just run a single video card then the GA-970A-UD3 AM3+ mobo will work well and allow upgrading to Bulldozer in the future. The GA-990XA-UD3 is also a good mobo.
You'll also need a quality PSU if you don't already have one.http://www.newegg.com/Product/Product.aspx?Item=N82E16813128519