nvidia optimus question

how do i get my nvidia graphics card to work at 100 percent performance as i
have a laptop and i want it to work at 100 percent so comment would be helpful thanks.

You mean that you want it to be stressed to full load?
here is a utility that might do the job, scroll down and download this version
FurMark 1.8.5

no i mean how can i know if the nvidia graphics card is working at 100 percent and not at a lower thing as nvidia optimus is a power option and i want the card to be at max performance and not at a power saver option

Control Panel\Hardware and Sound\Power Options\Edit Plan Settings\

Select "Change advance power settings." Then scroll down untill you see your graphics power settings. From there you can change it to the way you want it. I would also recomend changing the PCI Express setting to off.

the only problem with that is it only shows the intel graphics card but not the nvidia one

Then go to nvidia.com and fill in the form to get the latest driver for your card and install it.

What is the laptop model number?

The information the buyer gave you was concerning the cpu and not the video card. Without opening the laptop to check, you could right click on "computer" link in start menu, click on "manage" and go to "devices" ad look up the display adapters. Alternately yu can go to the nvidia website to download software / drivers and when they perform automatic scan it sould tell what type of video card it has (so long as its an nvidia card).

it is a 520m nvidia