I'm glad we waited a bit, there is a slight spin of the GTX780 to a GTX 990 (the 8xx series is the mobile family). The main thing is that it is the new Maxwell architecture which is a midlife extension to Keplar. Designed for "mobile first", it doubles the power efficientiy (watts/gflop) of Keplar.
At the very high end the GTX 980 will be unrivaled. It is roughly 10% faster than GTX 780 Ti and consumes almost 1/3rd less power for that performance. This is enough to keep the single-GPU performance crown solidly in NVIDIA’s hands, maintaining a 10-20% lead over AMD’s flagship Radeon R9 290X.
via AnandTech | The NVIDIA GeForce GTX 980 Review: Maxwell Mark 2.