Are you sure it's running on the dedicated nvidia card? This laptops have optimus technology which sometimes is buggy. my n53s asus has a led that tells me on which graphic card the laptop is running. its blue when on intel and white when on nvidia. Don't know if this 750 series have something to let you know which card is running. However, if your laptop isnt using the nvidia card because optimus doesnt do the job, i have found a fix for it:
Step 1. Download nvidiaInspector here:
http://www.guru3d.com/files_details/nvidia_inspector_download.htmlStep 2. Extract the .zip file and open nvidiaInspector.exe
Step 3. Click on the 2 tools button to the right of the "Driver Version" box.
Step 4. Under Profiles, navigate to your game.
Step 5. Under the Category "Other", there will be an option named "Enable application for Optimus". Change from "SHIM_RENDERING_MODE_USER_EDITABLE" TO "SHIM_RENDERING_MODE_ENABLE".
Step 6. Return to the previous list of steps to enable your nVidia GPU
i dont take any credits for this solution. found it on another forum, but dont remember where. i just copied this steps into a .txt file and i use it everytime i have problems with optimus.