VR-Zone has posted some specs for the upcoming 90nm G71 series already.

There will be two models as we have revealed before; the GeForce 7900 GTX and GeForce 7900 GT. GeForce 7900 GTX will be clocked at 650MHz core / 1.6GHz memory and has 512MB GDDR3 1.1ns memories onboard while GeForce 7900 GT will be clocked at 450MHz core / 1.32GHz memory with 256MB GDDR3 1.4ns memories.

GeForce 7900 Series Specs