When i start cuda debugging, Nsight return this error:
A CUDA context was created on a GPU that is not currently debuggable. Breakpoints will be dis
Maybe try falling back to an older version of Nsight.
I recently ran into this problem and installing an older version helped.
Your GT 720m is a compute capability 2.1 device (see here).
Attempting to debug CUDA code (e.g. set breakpoints) on a GPU that is also supporting (hosting) a display requires a compute capability 3.5 or higher device, to support preemption.
Your device does not meet that requirement, so because your GPU is hosting your laptop display, it cannot be used to set breakpoints in CUDA code.
Also note that the latest version of Nsight VSE (5.2 at this time) has officially dropped support for Fermi GPUs (yours is a Fermi GPU):
Note: Fermi family GPUs, and older families, are no longer supported with Nsight™ Visual Studio Edition 5.2 or better.