| The graphics card is a vital performance component | | | | DirectX Shader Models allows developers control over |
| of your computer, particularly if you play 3D games, or | | | | the appearance of an image as it is rendered on |
| work with graphics and video content. The graphics | | | | screen, introducing visual effects like multi-layered |
| card sits in an expansion card slot in your PC and it is | | | | shadows, reflection and fog. |
| specifically designed to process image data and output | | | | Fill rate |
| it to your monitor, enabling you to see it. A graphics | | | | This is the speed at an image can be rendered or |
| card works by calculating how images appear, | | | | "painted". This rate is specified in texels per second, |
| particularly 3D images, and renders them to the screen. | | | | the number of 3D pixels that can be painted per |
| 3D images and video images take a lot of processing | | | | second. A texel is a pixel with depth (3D). The fill rate |
| capacity, and many graphics processors are complex, | | | | comes from the combined performance of the clock |
| require fans to cool them and need direct power | | | | speed of the processor and the number of pixels it |
| supply. The graphics card consists of a graphics | | | | can process per clock cycle, and will tell you how |
| processor, a memory chip for graphics operations, and | | | | quickly an image can be fully rendered on screen. |
| a RAMDAC for display output. It may also include | | | | Vertices/triangles |
| video capture, TV output and SLI and other functions. | | | | Graphics chips don't work on curves, rather they |
| You can find the graphics card that suits you by | | | | process flat surfaces. A curve is created by multiple |
| comparing specification between brands and vendors | | | | flat planes arranged to look like a curve. 3D objects |
| on au | | | | are created with multiple triangular surfaces, |
| At au you can compare a great range of appliances, | | | | sometimes hundreds or even thousands, tessellated to |
| and assess them according to their specifications, | | | | represent the curves and angles of the real world. 3D |
| brands, prices and vendors. | | | | artists are concerned with the number of polygons |
| Graphics Cards | | | | required to form a shape. There are two different |
| What are your needs? | | | | types of specification: vertices per second (I.e., angles |
| The first decision you need to make is whether you | | | | the triangles), and triangles per second. To compare |
| need a graphics card for handling 3D images or | | | | one measure with the other, you have to take into |
| whether you are simply requiring 2D image rendering. | | | | account the fact that adjacent triangles share vertices. |
| For 2D requirements, you need only a low-cost | | | | Anti-aliasing |
| solution. In many cases, an integrated graphics solution | | | | A technique used to smooth images by reducing the |
| will suffice for 2D applications. | | | | jagged stepping effect caused by diagonal lines and |
| However with 3D graphics, the performance of the | | | | square pixels. Different levels of anti-aliasing have |
| graphics card will impact directly on the frame rate and | | | | different effects on performance. |
| image quality of 3D programs and games. The | | | | RAMDAC |
| differences between the low and high-end cards can | | | | The Random Access Memory Digital to Analogue |
| be substantial, both in cost and performance. | | | | Converter takes the image data and converts it to a |
| Rendering 3D graphics is like lighting a stage, both the | | | | format that your screen can use. A faster RAMDAC |
| geometry of the shapes in question and the lighting of | | | | means that the graphics card can support higher |
| it need to be taken into account. The geometry of an | | | | output resolutions. Some cards have multiple |
| image calculates the parts of an object that can and | | | | RAMDACs allowing that card to support multiple |
| can't be seen, the position of the eye and its | | | | displays. |
| perspective. The lighting is a calculation of the direction | | | | TV-out |
| of the light sources, their intensities and the respective | | | | Some graphics cards provide the option to connect a |
| shadows that occur. The second part to presenting a | | | | television via either a composite (RCA) or S-Video |
| 3D image is the rendering of colours and textures to | | | | connector. TV Out |
| the surfaces of the objects, and modifying them | | | | S-video Out |
| according to light and other factors. | | | | S-video In and S-video Out (VIVO) |
| Most modern graphics cards include a small microchip | | | | YPbPr Connection for HDTV |
| called the Graphics Processing Unit (GPU), which are | | | | DVI |
| provide the algorithms and memory to process | | | | Some graphics cards include a connector for DVI |
| complex images. They reduce the workload of the | | | | monitors, handy because a lot of LCD screens support |
| main CPU, and provide faster processing. Different | | | | DVI. DVI offers better image quality than the standard |
| graphics cards have different capabilities in terms of | | | | VGA connector. |
| processing power. They can render and refresh | | | | Dual-head |
| images up to 60 or more times per second, calculate | | | | Dual-head is a term used when two monitors are used |
| shadows quickly, create image depth by rendering | | | | side by side, stretching your desktop across both. |
| distant objects at low resolution, modify surface | | | | SLI (Scalable Link Interface.) |
| textures fluidly and eliminate pixelation. | | | | With SLI you can couple two graphics cards in your |
| What Specifications to Consider | | | | computer, enabling each card to take half the |
| Processor clock speed | | | | rendering thereby doubling the performance. |
| This impacts on the rendering capability of the GRU. | | | | When considering your graphics card, it pays to think |
| The clock speed itself is not the critical factor. Rather it | | | | about how much you need your computer to process |
| is the per-clock performance of the graphics | | | | your graphics output. Using a high end graphics card |
| processor, which is indicated by the number of pixels it | | | | with a high pixels per clock rating, large memory, fast |
| can process per clock cycle. | | | | processor and other features means that you can run |
| Memory size | | | | the latest games efficiently, or work in intensive |
| This is the memory capacity that is used exclusively | | | | graphics development. |
| for graphics operations, and can be as much as | | | | Different Models |
| 512MB. The more demanding your graphics | | | | While there are many vendors of graphics cards, there |
| applications are, the better you will be served with | | | | are actually only two major manufacturers of chips for |
| more memory on your graphics card. | | | | graphics cards. Nearly every graphics card on the |
| 16-32M | | | | market features a chip manufactured by either ATI or |
| 64M | | | | Nvidia. Cards using the same graphics chip will perform |
| 128M | | | | roughly the same as each other. However, even |
| 256M | | | | though they use the same chip, some feature slightly |
| 512M | | | | higher clock speeds, as well as manufacturer |
| 640M and more | | | | guaranteed overclocking-an even higher clock speed |
| Memory bandwidth | | | | than that specified. Other factors that will influence |
| One thing that can slow down 3D graphics | | | | your decision should include the amount of memory a |
| performance is the speed at which the computer | | | | card has (128MB, 256MB, 512MB) and its additional |
| delivers information to the graphics processor. A higher | | | | features, such as TV-Out and dual-screen support. |
| bandwidth means a faster data transfer, resulting in | | | | Use the search facilities at au to compare the |
| faster rendering speeds. | | | | features, prices and vendors of graphics cards. |
| Shader model | | | | |