It's better because it's the standard field, aftermarket over clocked cards are minuscule market in general, which run above the manufacturer Stock specifications. That's why they're called After-market Overclocked cards.
Not factory stock cards.
The graph you posted also clearly shows the GTX 780 is over clocked ( OC ), and even then the 2 year old 7970 isn't that far behind. 6 FPS, in ONE benchmark of Crysis 3.
So an overclocked GTX 780 is 6FPS faster than a Stock 7970 Ghz card from AMD.
So how would it then hold up against a NON-OC'd standard GTX 780, which still costs significantly more than the 7970/280x
Or If these same tests are then ran with that OC'd GTX 780 vs an OC'd 280X, would that not mean the 280X OC matches, it? Possibly beating it?
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Interesting that you are cherry picking. Stock benchmarks are the resounding standard for all measurements.
Yet in the graph you posted there's a 6FPS difference between the STOCK 7970Ghz with an Overclocked GTX 780.
Shows the 7970 is competing I'd say, despite running at stock speeds.
So at gaming then the benchmarks from all reputable sources shows the 7970/280x still competing against current NVIDIA offerings, and at 4k beating the GTX 770 in most, and just slightly being behind the GTX 780, some times an over clocked GTX 780 as you showed in that Hexus 4K display review.
http://hexus.net/tech/reviews/graphics/61201-amd-radeon-r9-280x-vs-nvidia-geforce-gtx-770-4k/
I mean if 4-6FPS is such a huge difference to all, well I guess the GTX770 just can't compete against the 2 year old 7970/280x