I am not so sure. I don't think HD8970 has any shot to hit 50-60% faster than HD7970GE unless HD8970 is 20nm Volcanic Islands. I don't think AMD will even come close to the Titan in a 1 die card until they hit 20nm. I would think the type of people buying $900 GPUs are also not the type who'll want to wait 12 months for something with similar performance for less money. Just look at the depreciation of cards like GTX280, 480 or 580. You can now get $499 GTX580 level of performance in an HD7850 OC for $150. This card is targeting those who want the best of the best as soon as it comes out. The same gamers are likely rocking 2 GTX680s/690, or similar in which case selling them and getting the Titan won't seem like a significant financial cost to side-grade to escape the SLI scaling requirement. Plus a lot of people just like to play with new toys. I expect some nice discounts on GTX680s in the used market shortly.
How? Their official road-map has nothing until Q3 2013. 20% faster HD8970 by Q4 2013 won't matter anymore since the Titan will have ruled the market for more than 7 months. I think AMD should keep themselves busy on drivers and game bundles. They have no chance of touching the Titan unless they pull some desperate official HD7990 SKU as a counter. Their best bet is to focus on the $100-300 GPU market segments where the competition is the most fierce rather than waste 100s millions of dollars attempting to counter something as impressive as the Titan. The Titan is like an i7 3970X since it targets a very niche super-high end market segment. With AMD's engineering resources and financial situation, it doesn't make sense to take such risks with such limited financial rewards when the competitor has so easily beaten the best they have in the HD7970GE. Even if they do try to make some 500mm2 HD8000 chip, it might be a total failure, and they would have wasted 6 months of time and resources. AMD doesn't have the luxury of the $5 billion ATI to pull stunts like that. The risk is just too high. What they should do is focus on price/performance in lower segments under $500 with HD7000 since that's what their strengths are. Seeing where Titan lands must be a scary thought for them since if they aimed at increasing performance of HD7970GE by 75% with their 20nm parts, those GPUs might easily get rolled over by Maxwell if a 28nm Titan comes in 60% faster than HD7970 Ghz (!!). Releasing drivers on time, fixing DX10/11 stuttering with GCN memory mgmt rewrite, things like that still matter for HD7000 series since it's targeting the key mainstream market segments.
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Videocardz reports that the GTX Titan would have computing power of 4.5 TFLOPS, with the GPU clock range of 800-900 MHz core clock. The memory may not reach the 6GHz GDDR5 mark. Paper launch on Feb 18th, with reviews the next day. They also state ROPs will be just 48. I thought GK110 with 14 SMX would have 56 ROPs since 8 SMX in GK104 is 32 ROPs (or 4 ROPs per SMX).