http://enthusiast.hardocp.com/article.html?art=MTYzNiwxLCxoZW50aHVzaWFzdA== said:
it is set to fall into the sweet spot somewhere between the Radeon HD 4870 1GB and the Radeon HD 4870 X2.
The RV790 is not a new architecture. It is a modified and tweaked version of the RV770 architecture, which has proven its worth since its launch in June of 2008. It boasts 1.36 teraflops of computing power on its GPU core with a maximum power rating of 190 watts.
The GPU clock rate has been increased by 100MHz to 850MHz, and the memory clock rate has been increased by 75MHz, for an aggregate data-rate frequency of 3.9GHz, which is 300MHz over the Radeon HD 4870. Those clock speed increases have resulted in a 4 GigaTexel/sec texture fill-rate increase, a 1.6 GigaPixel pixel fill-rate increase, and a 9.8 GB per second increase in memory bandwidth.
In fact, you guys are going to see some awesome overclocks from this GPU, upwards to 1GHz!