Im torn between msi twin frozr 680's in sli, or msi lightening 7970's in crossfire. Which do i choose? I have a 3770k, and a 1000w psu.
7970 Ghz will be faster, and probably OC higher, and unless your doing a bunch of crazy resolution + 3D stuff you wont need the 4GB, the 7970 also has Bus width in its favour.
I'd go 7970 unless you are really in love with PhysX and only play nvidia optimized games.