AMD's Radeon HD 7970 could not hold on to the single-GPU performance crown for too long. It lost it to NVIDIA GeForce GTX 680, and the upcoming GeForce GTX 670 threatens to damage its competitiveness even further. Reports suggest that AMD is working on a new Tahiti-based graphics card SKU, the Radeon HD 7970 GHz Edition. AMD unveiled the "GHz Edition" moniker to denote SKUs that come with engine clock speed ≥1 GHz. The new HD 7970 GHz Edition will come with reference core clock speed of 1050 MHz.
AMD needn't tinker with memory clock speed, as it already has a 384-bit wide GDDR5 memory interface compared to the GeForce GTX 680 and its 256-bit memory bus width. Sources told Atomic PC that improved yields and manufacturing processes have benefitted Tahiti just as well as GK104, and ES Tahiti chips from the latest batches "easily" hit 1250 MHz core. These batches could make custom-design graphics cards with extremely high core clock speeds possible.
Sources: Atomic PC, Engadget