• The tiny circuits on a graphics card can have a huge impact on their performance.Maria Toutoudaki/Photodisc/Getty Images
  
  Graphics cards use a multitude of specifications to differentiate themselves from the competition. They will report the speed of the graphics processor, the size of the on-board memory and just about everything else you can imagine. However, there are only a few key specifications that really affect the performance of the graphics card in a real-world situation.
  
  

Compatibility

• The compatibility of a graphics card with different software and hardware standards may be the most important specification to check. The DirectX support is an essential piece of information for comparing graphics cards. Additionally, you should check to make sure that the interface will work with your computer (AGP, PCI, PCI-express, etc.) and that it can provide output for your monitor and/or TV (DVI, HDMI, VGA, etc.).
  
  

Hardware

• Processor, RAM and the various interfaces between the parts of the video card will have a huge impact on how it can run 3D graphics. The primary specifications are the GPU (graphics processing unit) processing speed (expressed in Mega-Hertz or Giga-Hertz), the size of the dedicated RAM (expressed in Megabytes or Gigabytes) and the speed at which the RAM can be refreshed. In general, the higher the numbers, the greater the performance. Card manufacturers will tout many other numbers, but everything relies on these three numbers.
  
  

Benchmarks

• Similar to how a road test provides information on how a car performs under actual conditions, a benchmark is a piece of software that tests a graphics card in real-world conditions to render a result that can be easily compared with other cards. This is helpful when some manufacturers will use a lower GPU speed but higher memory bandwidth to achieve their results. Benchmarking provides the most accurate comparison of how graphics cards will perform.