I try cudaGetDeviceCount recently. From demo file multigpu.cu the comments say
// Note that in order to detect multiple GPUs in your system you have to disable
// SLI in the nvidia control panel. Otherwise only one GPU is visible to the
// application. On the other side, you can still extend your desktop to screens
// attached to both GPUs.
I have a window XP with NVidia 8500 and Telsa C870. If disable SLI, I get report of 2 GPUs and processiog time is slow (2000ms). If do not disable SLI, I det report of 1 GPU. The processing time is fast (30ms).
If I have C870, should I get report of 128 GPUs?
Why 2 GPUs process slow than 1 GPU?
Thanks for help!