hypergon :
Where is the 770 20% better than r9 280x and 10% weaker than 290x? DreamReview.com?
AMD cards (especially 280x/290/290x) are currently extremely overpriced in the US due to mining.
You should consider the gtx760, is a better card than 270x
Haha, very funny...
use any benchmark site, my favourite is videocardbenchmark.net
to calculate % difference --> 100-((variable benchmark score)/(controlled benchmark)*100)
so giving an example R9 280x has a score of 5,108 and GTX 770 has a score of 6,232
-----> 100-(5108/6232)*100= 100-(0.819*100)=100-81.9=18.1% ---> so to be precise the GTX 770 is 18.1% better...
Now I cant tell how well the GTX 770 does mining. nowadays I think its not worth mining with a video card, the difficulty just keeps growing and while the video cards are in MH/s the ASICs are in GH/s. I cant say much about mining performance but I can guarantee that gaming performance is higher.