iXBT Labs posted a review on the Gigabyte GTX260/275, HD 5870 Graphics Cards

The 5870 CF tandem puts up good performance. As we can see, it sometimes outperforms GTX 295 Quad SLI. Considering all innovations, including DX11, we can say that it's the most powerful duo with the most 3D features these days.

Gigabyte GTX260/275, HD 5870 Graphics Cards Review