SLI off and cudaGetDeviceCount = 1 (instead 2?)

I heard that better to disable SLI mode but after it, cudaGetDeviceCount returns 1 (not 2). Also I can’t use cudaSetDevice(1) - “invalid argument”. GPU-Z recognizes two GPUs but HWMonitor sees only one. I’m using mobile version of GF8s. Is here sth wrong with code or device?