Video card

From Wikipedia, the free encyclopedia

A video card, (also referred to as a graphics accelerator card, display adapter and numerous other terms), is an item of personal computer hardware whose function is to generate and output images to a display. The term is usually used to refer to a separate, dedicated expansion card that is plugged into a slot on the computer's motherboard, as opposed to a graphics controller integrated into the motherboard chipset.

Hardware

A video card consists of a printed circuit board on which the components are mounted. These include:

Graphics processing unit (GPU)

Main article: Graphics processing unit

The GPU is a microprocessor dedicated to manipulating and rendering graphics according to the instructions received from the computer's operating system and the software being used. At their simplest level, GPUs include functions for manipulating two-dimensional graphics, such as blitting. Modern and more advanced GPUs also include functions for generating and manipulating three-dimensional graphics elements, rendering objects with shading, lighting, texture mapping and other visual effects.

Video memory

Unlike integrated video controllers, which usually share memory with the rest of the computer, most video cards have their own separate onboard memory, referred to as video RAM (VRAM). VRAM is used to store the display image, as well as textures, buffers (the Z-buffer necessary for rendering 3D graphics, for example) and other elements. VRAM typically runs at higher speeds than desktop RAM. For the most part, current graphics cards use GDDR3 or GDDR4 although DDR, DDR2 or any other technology may be used.

Video BIOS

The video BIOS or firmware chip is a chip that contains the basic program that governs the video card's operations and provides the instructions that allow the computer and software to interface with the card. It contains information on the memory timing, operating speeds and voltages of the processor and ram and other information. It is possible to re-flash a bios although this is typically only done by video card overclockers.

PCI Express

PCI Express is the newest slot that most new cards fit into. It comes in a variety of speeds which vary in size proportionate to the speed. The older AGP slot is still used on legacy motherboards and low end current motherboards, although it will eventually be phased out; most cards are made in both these formats for now. Depending on what speed interface used, PCI Express video cards may have a higher speed interface than AGP, leading to increased performance on the high end cards. PCI Express may be up to twice the speed of the AGP interface. PCI Express, aka PCIe, should not be confused with the long outdated PCI format, which predates even AGP.

See also

• Computer graphics
• Computer hardware
• List of manufacturers
• Overclocking Wiki, general computer and video card information tweaking

References

Mueller, Scott (2005) Upgrading and Repairing PCs. 16th edition. Que Publishing. ISBN 0-7897-3173-8

en:Graphics card