NVIDIA's energy-efficiency leap achieved on existing 28 nanometer process, using the "Maxwell" based GM107, appears to have rattled AMD. The company is reportedly attempting a super-efficient, 28 nm, mid-range chip of its own, codenamed "Tonga." The chip could power graphics cards that compete with the GeForce GTX 750 Ti and GTX 750. The chip is likely to be based on Graphics CoreNext 2.0 micro-architecture, the same one that drives "Hawaii," which means AMD isn't counting on the micro-architecture for efficiency gains. It could feature an evolution of PowerTune, which works closer to the metal than its existing implementation on "Hawaii." Other features could include Mantle, TrueAudio, and perhaps even XDMA CrossFire (no cables needed). The chip could be wired to up to 2 GB of memory.

Another equally plausible theory doing rounds is that "Tonga" could be a replacement to "Tahiti Pro," designed to compete with the GK104 at much lower power footprint (than "Tahiti"), so AMD could more effectively compete with the GeForce GTX 760. The chip could be similar in feature-set to "Tahiti," with a narrower memory bus (256-bit wide), but higher clock speeds to make up for it. If this theory holds true, then "Tonga" could disrupt both Tahiti Pro and "Curacao XT." Curacao XT (R9 270X) is designed to offer a value-conscious alternative to the $250 GTX 760. The R9 280 is competitive in performance, but takes a beating on the energy-efficiency front, and is also costlier to manufacture, due to the higher transistor count and four additional memory chips. We could hear more at Computex 2014.