The card works at the reference 612 MHz for GPU and 2160 MHz for the memory. Another difference between this and the GTX is in the Shader clocks, GTX Shaders works at 1350MHz while the Ultra works a little faster, at 1500 MHz.
Higher clocks on GPU and memory should result in higher performance, up to 10-15%. There is 15% more memory bandwidth, which is now 101.3 GB/s compared to a GTX which has "only" 86 GB/s.
Today we have a short preview of the card for you, so that you can see that there is a boost in performance when compared to the last high-end card from Nvidia, the 8800 GTX.
They found the card scores about 6% better in 3DMark06 and in real gaming benchmarks the card scores up to 15% better than the GeForce 8800 GTX in F.E.A.R. at high resolutions (2048 x 1536 pixels).