Do yourself a favor and drop the GTX 670. GTX 670 and cutting costs in a build don't fit in the same sentence.
Either go for a factory overclocked GTX 660Ti which is $50 cheaper and performs as good as a GTX 670, or be smarter and go for this:
http://www.guru3d.com/articles_pages/his_radeon_7950_x_iceq_review,1.html
Costs the same as a GTX 660Ti, is factory overclocked, and shows the GTX 670 every corner of the room. If you overclock it further you have a 300$ which performs nearly, if not the same, as an HD7970 or a GTX680 which are expensive high-end cards. In addition to that, you'll probably get Crysis 3 and Bioshock Infinite free with this card. There's just no reason to spend $350-$400 on a card that doesn't necessarily perform better than a $280-$300 card.
Hell, the guys from hardware.info managed to overclock this card and get a 3DMark score of P11132, and overclock it all the way to 1150Mhz. With a $300 card. I rest my case.
If you really want to stick with the Nvidia cards, go for a $300 factory overclocked GTX 660Ti from ASUS or MSI.