The theory of three
We've chosen to build our three-way SLI rig with GeForce 8800 Ultras because, hey, if you're gonna go all out, you might as well go all out. The Ultra is a very powerful graphics card in itself, but here's what happens, in theory, if you put three of them together.
|
Peak pixel fill rate (Gpixels/s) |
Peak bilinear texel filtering rate (Gtexels/s) |
Peak bilinear FP16 texel filtering rate (Gtexels/s) |
Peak memory bandwidth (GB/s) |
Peak shader arithmetic (GFLOPS) |
|
| GeForce 8800 GT | 9.6 | 33.6 | 16.8 | 57.6 | 504 |
| GeForce 8800 GTS | 10.0 | 12.0 | 12.0 | 64.0 | 346 |
| GeForce 8800 GTS 512 | 10.4 | 41.6 | 20.8 | 62.1 | 624 |
| GeForce 8800 GTX | 13.8 | 18.4 | 18.4 | 86.4 | 518 |
| GeForce 8800 Ultra | 14.7 | 19.6 | 19.6 | 103.7 | 576 |
| GeForce 8800 Ultra 2-way SLI | 29.4 | 39.2 | 39.2 | 207.4 | 1152 |
| GeForce 8800 Ultra 3-way SLI | 44.1 | 58.8 | 58.8 | 311.0 | 1728 |
| Radeon HD 2900 XT | 11.9 | 11.9 | 11.9 | 105.6 | 475 |
| Radeon HD 3850 | 10.7 | 10.7 | 10.7 | 53.1 | 429 |
| Radeon HD 3870 | 12.4 | 12.4 | 12.4 | 72.0 | 496 |
| Radeon HD 3870 X2 | 26.4 | 26.4 | 26.4 | 115.2 | 1056 |
The numbers are staggering. 311 GB/s of memory bandwidth, more than 1.7 teraflops of shader arithmetic, and nearly 60 Gtexels per second of FP16 texture filtering capacity—almost five and a half times that of a GeForce 8800 GT. Of course, extracting the full potential from three graphics cards is much more difficult than it is with one graphics card, but still... wow.
Our three-way rig leads all contenders in 3DMark's synthetic tests of GPU power, with the lone exception of the simple vertex shader test, where it seems to run into a scaling issue. In terms of delivered multitextured fill rate, the three-way SLI system roughly doubles the Radeon HD 3870 X2, AMD's current fastest graphics solution.
