A computers graphics card works with the processor to form the correct image, the processor gets information from the software and sends that information to the graphics card. The graphics card then has to calculate how to arrange the pixels in order to show the correct image, the graphics card then sends the correct image through a HDMI/VGA cable (or any other usable cable) and allows the person to see the image on the screen. In a game, the graphics card has to be able to produce a 3D image very quickly and well and does this by firstly putting all the information into a wireframe, then it has to fill in the remaining pixels to create the full thing and then can add lighting, colour and textures. Different graphics cards have different speeds in which they can do this, a more expensive graphics card will be able to do this process faster which will mean the game will run smoother. Also depending on what graphical settings the user uses whilst playing the game can also affect how smooth the game will run, and how much load there will be on the graphics card.