7970 6gb or r9 280x dual-x?

Solution
http://www.techpowerup.com/reviews/Gigabyte/R9_280X_OC/26.html

The R9-280X is a rebadged HD7970 so there's no advantage on paper. It comes down to how well it's designed (including the cooler), the binning of the GPU if any, and the VRAM.

If the ONLY difference is that the HD7970 has more VRAM then go for that card.

Also, be careful of the 300 series. For example, the R9-380 seems to trade blows with the R9-280 but has far less cores (it's due to better cooler and high clock speeds) so does this mean the R9-280 wins if you overclock it over stock? Probably.
http://www.techpowerup.com/reviews/Gigabyte/R9_280X_OC/26.html

The R9-280X is a rebadged HD7970 so there's no advantage on paper. It comes down to how well it's designed (including the cooler), the binning of the GPU if any, and the VRAM.

If the ONLY difference is that the HD7970 has more VRAM then go for that card.

Also, be careful of the 300 series. For example, the R9-380 seems to trade blows with the R9-280 but has far less cores (it's due to better cooler and high clock speeds) so does this mean the R9-280 wins if you overclock it over stock? Probably.
 
Solution