I have installed a GeForce 8800GTX board on an Intel branded ATi motherboard with ATi integrated graphics. When I installed CUDA, the ATi graphics were disabled, and the 8800GTX was the primary monitor. I read on other parts of the CUDA forums that it’s best to use another card for your Windows Desktop and reserve the CUDA card for CUDA calculations - otherwise your system may hang during long kernel executions. So I installed the ATi drivers, and then told Windows to use the ATi graphics as the primary monitor, and not to extend the Windows Desktop to my 8800GTX.
It seems that doing so messed up my system - the Windows Display control panel now reports that “The currently selected graphics driver cannot be used. It was written for a previous version of Windows, and is no longer compatible with this version of Windows. The system has been started using the default VGA driver.”
This is a mistaken error message, as far as I can figure out, since the driver versions are listed correctly in Control Panel->System->Hardware->Device Manager, and the device manager reports that both display adapters are working properly.
Whatever the cause of this error message, CUDA fails to find the 8800GTX at runtime and therefore won’t run anymore.
I’m going to disable the ATi graphics and attempt to use the 8800GTX as my primary display again, so that I can continue with my CUDA programming, but I was hoping someone on this forum would know if there is a solution to this problem, or whether this arises out of inherent incompatibilities between the ATi drivers and the nVidia drivers. It would be nice if I could reserve my 8800GTX for CUDA computations only.