Games using integrated graphics card instead of Nvidia card

when your comp uses normal apps it has the integrated graphics on. it will automatically switch to the dedicated gpu when you play your game. That is why the benchmark test is off.

I had the same problem as you, but I finally found a fix for it through the Nvidia Control Panel. I have an integrated Intel HD Graphics 4600 and an Nvidia Geforce GT 750M

Right click on the desktop and open nvidia control panel.
Then head to the "manage 3D settings" drop down under 3D settings.
Then under the global settings tab, underneath preferred graphics processor, change it from auto detect to high performance graphics processor.
Now your laptop should be using your Nvidia GT 630M for almost everything, including your steam games.

For games that use DX9 you can also try the optimus fix : http://skyrim.nexusmods.com/mods/33227//?

I'm not sure you can run Sleeping Dogs in DX9 though

There is a setting that force the pc to use the integrated card when laptop is not charging. For power saving reason.

Go to BIOS settings and disable the integrated card.