Both are nice cards. I was just trying to see what we as a community felt was the best of the generation. I believe the clear winner is the 7970 GHZ.
If we are talking cream of the crop HD7970 Ghz vs. GTX680, in my eyes the Asus Matrix Platinum would beat any single GPU this round. The only decider is then NV-specific features (PhysX, CUDA, 3D vision), not performance.
In the most demanding titles, things can get real nasty for the GTX680.
At multi-monitor gaming, GTX680 is not even on the map.
"That said, we have to wonder why anyone would bother with the GeForce GTX 680 4GB for extreme resolutions when the Radeon HD 7970 GHz Edition was constantly faster at both 5040x1050 and 7680x1600. In fact at 7680x1600 the 7970 GHz Edition was on average
20% faster than the GeForce GTX 680 4GB in the half dozen games that we tested with."
http://www.legionhardware.com/articles_pages/gigabyte_geforce_gtx_680_4gb,6.html
NCIX even tested it against an overclocked GTX680 Lightning and the Matrix
still won. This is not a surprise since HD7970 is faster per clock so there is no way you can beat a 1300mhz HD7970 unless you overvolt GTX680 to 1450mhz or something.
Contrary to popular beliefs that Cats 12.11s put HD7970 Ghz over the top, HD7970 Ghz was already faster as early as June 2012 and this was widely documented by most professional reviews. Cats 12.11s actually extended 7970 Ghz's lead but NV lost the single GPU performance crown as early as Cats 12.7 betas. Of course most people on our forum didn't acknowledge this back then because they were too busy discussing the noise levels and power consumption of the non-existent retail reference designed HD7970 Ghz card:
http://www.techpowerup.com/reviews/AMD/HD_7970_GHz_Edition/28.html
And then there is the case of 1200mhz Sapphire HD7970 6GB TOXIC. That card took out the fastest factory pre-overclocked GTX680 (a 1267mhz Galaxy/KFA2 White edition):
"In 7 out of 11 tests, The Sapphire HD7970 6GB Toxic Edition outperformed the KFA2 GTX680 Limited OC Edition."
http://www.kitguru.net/components/graphic-cards/zardon/sapphire-hd-7970-6gb-toxic-edition-review/25/
So really, stock vs. stock, OC vs. OC, HD7970 Ghz had GTX680 beaten 5 months ago. At high resolution with the latest drivers, even a stock 925mhz HD7970 is faster than GTX680 and after-market HD7970 cards are in another league entirely.
No matter how we slice it, NV went from having a clear performance lead with GTX280/285/480/580 to losing the single GPU performance crown. They'll probably get it back next year with the GTX780 but GTX680 was overall one of their least impressive showings since GeForce 7. What made GTX680 so sour in my mouth was that nV continued to charge more for it after June 2012 despite selling a slower card. When companies charge more $ for less performance, that stuff doesn't fly well with me.
Of course as some mentioned if all you play is a particular game that runs faster on 1 brand or the other, well then pick based on that 1 game!