Onboard graphics detected not graphics card

Hey everyone.... How r u all??? Nice to meet u all..... ^_^

well my friend bought a laptop it has on board graphics and also a additional nvidia graphics... now when I run game the on board graphics card is getting detected and not the nvidia card.. I tried in bios but in the display part there are only 2 options 1 is optimus whic allows bot nvidia vga and intel vga to work and the other one allows only the intel vga to work... so is there a way to make games recognise nvidia or can I disable onboard graphics through device manager??

laptop model: lenovo ideapad z570

graphics card: Nvidia geforce gt 540m

and one more thing...In one of the game I checked PES 2012 it shows as its using onboard graphics.. and I tried arkham city and tried enabling hardware acceleration physx but it said the laptops hardware doesnt support it....

one more thing I just went to nvidia control panel and in there 3d settings and there global settings its written there preferred graphics processor is integrated graphics.. and I couldnt change it.....

can I disable the onboard graphics card in device manager???

thanks....

Hi , The option is the one where the nvidia card and intel on-board are shown, and the BIOS should select the nvidia card as priority if it can, and has a choice.
It's sometimes known as 'Primary Video' & the option is called PEG.
Make sure you save the settings when you exit or they won't be changed from before.