If you have multiple cards, use the '-i' parameter to select a specific card.  On my machine with a Quadro2000 and Tesla2050, I initially got this error:
C:Program FilesNVIDIA CorporationNVSMI&gt;nvidia-smi.exe -dm 1

Unable to determine display mode for GPU 0000:0F:00.0: Not Supported

Specifying the second device (zero-indexing) got it working:
C:Program FilesNVIDIA CorporationNVSMI&gt;nvidia-smi.exe -i 1 -dm 1
Set driver model to TCC for GPU 0000:42:00.0.
Reboot required.

