Nvidia's 'Fermi' GPU architecture revealed
 

Those numbers set the stage. We're guessing from here, but let's say 1500MHz is a reasonable frequency target for Fermi's stream processing core. That's right in the neighborhood of the current GeForce GTX 285. If we assume Fermi reaches that speed, its peak throughput for single-precision math would be 1536 GFLOPS, or about half of the peak for the Radeon HD 5870. That's quite a gap, but it's not much different than the gulf between the GeForce GTX 280's single-issue (and most realistic) peak and the Radeon HD 4870's—yet the GTX 280 was faster overall in graphics applications and performed quite competitively in directed shader tests, as well.

Double-precision floating-point math is more crucial for GPU computing, and here Fermi has the advantage: its peak DP throughput should be close to 768 GFLOPS, if our clock speed estimates are anything like accurate. That's 50% higher than the Radeon HD 5870, and it's almost a ten-fold leap from the GT200, as represented by the GeForce GTX 280.

That's not all. Assuming Nvidia employs the same 4.8 Gbps data rate for GDDR5 memory that AMD has for Cypress, Fermi's peak memory bandwidth should be 230 GB/s, again roughly 50% higher than the Radeon HD 5870, which has a total memory bus width of 256 bits.

http://techreport.com/articles.x/17670