Computer isnt reading video card windows 7?

My computer is not readung my Video card that I put in it keeps reading the on board video card I dont understand why or what to do to fix it the video card I put in is a NVIDIA Geforce 6800 GS, however I went on to the NVIDIA website to try to install drivers but it couldnt fid it. My monitor is running through the NVIDIA video card, but the actual card isnt running, and the NVIDIA website kept showing me the onboard graphics card. I tried to disable the onboard to make it read the alternate one and it hasnt worked, any ideas would be great!|||A graphic card is primarily used to ensure a smooth gaming experience. However, if video card crashes, hangs or stutters in a middle of a game, it may be due to overheating. You can resolve this problem by underclocking your video card, which includes slowing down the speed of video card to cool it down and reduce its power consumption. Sometimes, problems in graphic card can also be due to Accelerated Graphics Port, which is used to connect a video card to the motherboard. Instability issues with Accelerated Graphics Port may result in video data corruption. You can resolve this issue by simply using a slower multiplier.|||You are using the automatically detect the nvidia graphic card mode at the nvidia website ,use the manual mode input the info ,6 series,geforce 6800 GS, and the os , click the search, it should find the latest graphic driver download it and save to desktop, shut down the pc, take out the graphic card, restart go to the bios ,change from on board to agp ,shutdown ,install the graphic card,restart

let the pc boot and load, found new hardware will show up cancel it and install the graphic driver that was saved to the desktop