From this post:
From NVIDIA Control Panel
3D Settings->Manage 3D Settings
Tab "Global setttings"
Preferred Graphics Processor
Select : High performance NVIDIA rocessor
Alternatively, you could check if you can set the Nvidia card as the preferred graphics card for the game you're using. You could try what is described here:
- Go to the NVIDIA Control Panel by right clicking on your desk top and clicking on "NVIDIA Control Panel".
- In the default screen that pops up (it should be "manage 3D settings", and the "Program Settings" tab should be automatically selected), under "1. Select a program to customize:" hit the "Add" button.
- From here, navigate to the folder where your steam games are located. For me, it is C:\Program Files (x86)\Steam\steamapps\common.
- Select the folder for the game you want to use your NVIDIA card for, and find the .exe for that game (it's usually right in the main game folder). Select it and hit open.
- Then, under "2. Select the preferred graphics processor for this program:" open the drop-down menu and select "High-performance NVIDIA processor".
- Finally, hit apply in the far bottom right corner, and you should be good to go!
According to the author of what I've quoted, this should work for any .exe.