Good choices, particularly the graphics card and processor. I am not to sure on the motherboard as unless you intend to put another graphics card in at a later date, which with the 670 will not be necessary. Then you are paying for facilities that you are not going to use or need. You could have a look at this board as an alternative , still has all that you need but a lot cheaper.
Alienware 17 R4 2017 review