"SLI Frame Rendering: Combines two identical NVIDIA Quadro PCI Express graphics cards with an SLI connector to transparently scale application performance on a single display by presenting them as a single graphics card to the operating system."Therefore, we can use SLI in conjunction with CUDA to have two identical cards on my machine (any 8800 or Quadro 5600 or 4600) and program 256 multiprocessors as though they were one GPU?

SLI and CUDA are orthogonal concepts. The first is for automatic distribution of rasterization, the second is for addressing direct execution of code on the GPU. CUDA is not used for rendering (on- or offscreen). That is when using CUDA you can simply list all available cards in the machine and directly submit code to execute. This code has nothing to do with shader code - it is C-like. So you have a lot more control of what happens where and when.No, in general you don't want to use SLI if you plan on using the GPUs for compute instead of pure graphics applications. You will be able to access both GPUs as discrete devices from within your CUDA program. Note that you will need to explicitly divide work between the GPUs.

I don't have an explanation for why SLI isn't desirable for compute applications,

thank you for your answer, I'll explore that

Your welcome ..

If u do lyk comment u can vote up else its ok. :)

Dear Sidi,

I think that SLI enables to reduce significantly the costs of data transfer between GPUs.

Thanks.

Thakns Mostafa, I think so

I think that SLI primarly transfers synchronization commands. The impact on transfering bandwidth is none or minimal (compare bus width: PCIe and SLI)