Tom's Hierarchy chart isn't that great comparing cards between a short timeframe, its better for comparing performance tiers between generations, for example the GTX 690 is clearly a little bit faster than HD 7990, same with the GTX 780 vs the HD 7970Ghz
IMHO and being an AMD user the chart should be something like this 270X>HD 7950>>HD 7970>>GTX 680>7970 Ghz~GTX 770/280X>>GTX 780>>GTX TITAN>>>>HD 7990>GTX 690
Being each ">" about 5% difference
Most of the time AMD wins on the price/performance department though

PS Vita and PC gamer
CPU Intel i5 2500K at 4.5 Ghz / Gigabyte Z68 Mobo / 8 Gb Corsair Vengeance 1600 mhz / Sapphire HD 7970 Dual X Boost / Corsair Obsidian 550d







