In my os device manger under display adapters, it has two things

[Naer]

one intel hd graphics

and another one NVidia nvs 3100m

which one is being used?

 

[Deders]

Which one is your monitor plugged into?

 

[Naer]

Which one is your monitor plugged into?

its a laptop

 

[ShintaiDK]

Install the manufactors optimus drivers.

You can switch between the 2.

 

[night.fox]

they are both used. intel hd when only less load or normal task and discrete gpu when heavy gpu usage like gaming.

i dont know model of yours but on my msi, the power button turns orange when discrete gpu is in use and it turns white again if i stop playing