Only one GPU?

When i use Parallel Nsight 2.1 ,it gives the such information:Nsight debugging cannot be performed when there is only one GPU

Why? my card is GT 420M.When i run the template program in the SDK, it shows that my graphic card has 2 processor!
How can i solve this problem?

That is a single core video card. there are very, very few dual gpu cards. Are you sure the4 sdk isnt saying that you have a dual core cpu, not gpu?

Does all versions of Parallel Nsight require video card has more than one core? Or is there any solution to solve that problem?

You will need 2 cards for debugging with Parallel Nsight. In Debug Mode the whole card is blocked. So you need a second card for the normal task a graphic card does.