I have mounted two cuda-enabled GF video cards on my PC. The first one is used for display; the second one is idle. Then my question is: what is in the video memory in the second card? empty or something else? Thanks.
Just connect the monitor to it and see what it says.
If you extend the desktop to your second graphics card, a portion of its VRAM will have the display content.
otherwise, it is just resting happily.