Have 18 laptop and when I want to change to the GPU via the FN/F5 hot key it take about 3 reboots before it see the video card. Any idea why it could do this, running windows 8.1 Pro with all drives and software installed.
Most likely your video card is going bad. I would update to latest Nvidia drivers and then download becnhmark software like Catzilla and stress test the video card.
In the Nvidia Control Panel you can choose which programs will run using Geforce video card so you dont have to switch and reboot every time.