Taking advantage of SLI?



With an NVidia SLI setup, I see that SLI is indeed being utilised when I run a game (I can see the GPU temperatures for both cards go up to eg 85degs), however after intense usage of my application I see that only 1 GPU increases with temperature and therefore I assume that SLI is not enabled. But my understanding was that SLI is supposed to be transparent to the application. I know a game would exercise the card much more that my program, however, I would have thought the GPU load would still be shared, resulting in both GPU temps increasing slightly.

Can you please help correct my understanding of what I am seeing with regard to SLI?

Thanks for any pointers,