Video cards can be connected to monitors which may be CRT, LCD or even a projector. CRT monitors use VGA cables, while LCD monitors use DVI cables. Video cards can have different display resolution standards, such as SVGA, HVGA, and XGA. If you use a big monitor, then you will need a better video card. Video cards manipulate the pixels on a screen and can be used for multiple screen displays too. Software programs communicate with video cards to decide what to display on the screen. Tuners for analog TV signals need to encode into MPEG, but tuners for digital TV signals are more complex.
The important factors to look at when buying a video card are the GPU (the graphical processing unit) and the amount of video memory. All video cards have GPUs, and the three main manufacturers of GPUs are NVIDIA, ATI and Matrox. ATI's most popular GPU is called Radeon, while NVIDIA's most popular GPU is called GeForce. Other manufacturers use these GPUs to make their own video cards. Video cards also have onboard memory. Memory speeds of video cards are usually faster than memory speeds of main memory, which is Random Access Memory. Video cards also have 3D accelerators used to create 3D images. The refresh rate which is measured in Hertz is the number of times the screen is drawn in a second. If the refresh rate is too low, then there is flicker on screen.
DirectX is used for multimedia programming. Windows XP uses DirectX 9, while Windows Vista uses DirectX 10, although the Aero interface doesn't use DirectX 10. A video card that is DirectX 10 capable can be used with Windows XP, while a video card that is DirectX 9 capable can be used with Windows Vista.
Graphics can be either 2D or 3D. 2D graphics is used for productivity software such as Microsoft Word and web browsers such as Microsoft Internet Explorer. An integrated video card which has the video card and the processor on the same chipset is suitable for low end computers used for such 2D graphics. However, if you want to watch video or are using graphics intensive programs such as Adobe Photoshop, then an integrated video card will not be sufficient.
Both the CPU and the video card integrate the 3D graphics effect. 3D graphics is used for games such as Doom and Quake. Gamers need high-end video cards, or even a dual video card. A dual video card is two identical video cards connected by an interface. The interface may be SLI (Scalable Link Interface) for NVIDIA cards and Crossfire for ATI cards. If designers want to use 3D graphics software such as Maya or computer aided technologies then they need the ATI FireGL video card or the NVIDIA Quadro video card.
Earlier, the PCI interface was used to connect the video card, the sound card and the network card to the computer, but it was quite slow. Later, the AGP interface was used to especially connect video card to the computer, and it was much faster than PCI. Now, the PCI Express interface is used to connect the video card to the computer. While most cards need one channel to connect to the computer, video cards need 16 channels to connect to the computer.