Dec 17 2008
Video Card
A video card, also known as a graphics accelerator card, display adapter, or graphics card,
is a hardware component whose function is to generate and output images
to a display.
Some video cards offer added functions, such as video capture, TV
tuner adapter, MPEG-2 and MPEG-4 decoding, FireWire, mouse, light pen,
and joystick connectors, or even the ability to connect multiple
monitors.
A common misconception regarding video cards is that they are
strictly used for video games. Video cards instead have a much broader
range of capability. Being specialized for video, output video cards
improve what a computer monitor displays. As well, they play a very
important role for graphic designers and 3D animators, who tend to
require optimum displays for their work as well as faster rendering in
order to efficiently tone up their work.
Two ATI Graphics Cards
Video cards are not used exclusively in IBM type PCs; they have been
used in devices such as Commodore Amiga (connected by the slots Zorro
II and Zorro III), Apple II, Apple Macintosh, Atari Mega ST/TT
(attached to the MegaBus or VME interface), Spectravideo SVI-328, MSX,
and in video game consoles. (Wikipedia.com)
Components
THE GPU
A GPU is a dedicated graphics microprocessor optimized for floating point calculations which are fundamental to 3D graphics rendering. The main attributes of the GPU are the core clock rate, which typically ranges from 250 MHz to 850 MHz, and the number of pipelines (vertex and fragment shaders), which translate a 3D image characterized by vertices and lines into a 2D image formed by pixels.
Video Bios
The video BIOS or firmware
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 may contain information on the memory
timing, operating speeds and voltages of the graphics processor and RAM
and other information. It is sometimes possible to change the BIOS
(e.g., to enable factory-locked settings for higher performance)
although this is typically only done by video card overclockers, and
has the potential to irreversibly damage the card.
NVidia Graphics Card
Video Memory
If the video card is integrated in the motherboard, it may use the computer RAM
(lower throughput). If it is not integrated, the video card will have
its own video memory, called Video RAM. The memory capacity of most
modern video cards range from 128 MB to 4.0 GB.
Since video memory needs to be accessed by the GPU and the display
circuitry, it often uses special high speed or multi-port memory, such
as
| Type | Memory clock rate (MHz) | Bandwidth (GB/s) |
|---|---|---|
| DDR | 166 - 950 | 1.2 - 30.4 |
| DDR2 | 533 - 1000 | 8.5 - 16 |
| GDDR3 | 700 - 1800 | 5.6 - 54.4 |
| GDDR4 | 1600 - 2400 | 64 - 156.6 |
| GDDR5 | 3000 - 3800 | 130 - 230 |
VRAM, WRAM, SGRAM, etc. Around 2003, the video memory was typically based on DDR technology. During and after that year, manufacturers moved towards DDR2, GDDR3 and GDDR4
even GDDR5 utilized most notably by the ATI Radeon HD 4870. The memory
clock rate in modern cards are generally between 400 MHz and 3.8 GHz.
Outputs
The most common connection systems between the video card and the computer display are:
| Video Graphics Array (VGA) (DB-15) | Analog-based standard adopted in the late 1980s designed for CRT displays, also called VGA connector. Some problems of this standard are electrical noise, image distortion and sampling error evaluating pixels. |
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| Digital Visual Interface (DVI) | Digital-based standard designed for displays such as flat-panel displays (LCDs, plasma screens, wide High-definition televisionnative resolution. displays) and video projectors. It avoids image distortion and electrical noise, corresponding each pixel from the computer to a display pixel, using its |
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| Video In Video Out (VIVO) for S-Video, Composite video and Component video | Included to allow the connection with televisions, DVD players, video recorders and video game consoles. They often come in two 9-pin Mini-DIN connector variations, and the VIVO splitter cable generally comes with either 4 connectors (S-Video in and out + composite video in and out) or 6 connectors (S-Video in and out + component PB out + component PR out + component Y out (also composite out) + composite in). |
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Video Cards also have the ability to connect to each other to load frames faster.(more info in separate blogs)
With ATI it is called Crossfire
And with NVidia It is called SLI Mode
