How to Choose a graphcis card - Author unknown

Graphics Card.

A good overall measurement of a card's performance is its frame rate, measured in frames per second (FPS). The frame rate describes how many complete images the card can display per second. The human eye can process about 25 frames every second, but fast-action games require a frame rate of at least 60 FPS to provide smooth animation and scrolling. Components of the frame rate are:

Triangles or vertices per second: 3-D images are made of triangles, or polygons. This measurement describes how quickly the GPU can calculate the whole polygon or the vertices that define it. In general, it describes how quickly the card builds a wire frame image.

Pixel fill rate: This measurement describes how many pixels the GPU can process in a second, which translates to how quickly it can rasterize the image.

Overclocking
Some people choose to improve their graphics card's performance by manually setting their clock speed to a higher rate, known as overclockings. People usually overclock their memory, since overclocking the GPU can lead to overheating. While overclocking can lead to better performance, it also voids the manufacturer's warranty.

The graphics card's hardware directly affects its speed. These are the hardware specifications that most affect the card's speed and the units in which they are measured:

• GPU clock speed (MHz)
• Size of the memory bus (bits)
• Amount of available memory (MB)
• Memory clock rate (MHz)
• Memory bandwidth (GB/s)
• RAMDAC speed (MHz)

The computer's CPU and motherboard also play a part, since a very fast graphics card can't compensate for a motherboard's inability to deliver data quickly. Similarly, the card's connection to the motherboard and the speed at which it can get instructions from the CPU affect its performance.