Applications which tax the GPU will see tremendous performance improvements of up to 2x with SLI technology when using two graphics cards. Most of today's hottest games and as well as next-generation games fall into this category. However, some applications, typically older generation applications, are limited by factors other than the GPU's processing power.
The most common limitation is the CPU. If an application becomes CPU bound, no additional graphics power can improve performance. This situation is most common at low screen resolutions like 1024x786 with no additional functionality turned on. Turning on antialiasing and anisotropic filtering, or switching to higher resolutions, can often move the processing requirements back to the GPU.
For CPU-bound applications, NVIDIA offers a new SLI rendering mode called SLI Antialiasing. This rendering mode allows you to enable SLI8x or SLI16x antialiasing and enhance the visual quality of any gaming application.