There is a scene that I can not render with all the cards. Randomly when I launch the render in batch mode, in the middle of the samples, this message is displayed.
"The Nvidia Geforce GTX 780 Ti device is not removable and can not be ejected or unplugged"
This error only appears in one scene.
Windows 7 64 bits
32 Gb RAM
Nvidia GTX Titan
2x Nvidia GTX 780 Ti
Nvidia GTX 460 (just for monitor).