Video card
From Saferpedia
A video card also called Graphic Acceleration Card or Video Adapter is a card that generates output images to a display. Many video cards have additional features like accelerate graphic for 3D scenes, video capture, TV output, MPEG-2 and MPEG-4 decoders, FireWire or the capacity to connect several displays.
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History
The first video adapter was developed and launched by IBM, with their first PC in 1981. It was a monochrome graphic card (MDA - Monochrome Display Adapter) and was working only in text mode representing 80 columns and 25 lines on the screen. It had a video memory of 4 KB and one color. In time the video card industry evolved as it is showed in the table below.
| Year | Text mode (columns/lines) | Graphic mode (resolution/colors) | Memory | |
|---|---|---|---|---|
| MDA - IBM Monochrome Display Adapter | 1981 | 80×25 | - | 4 KB |
| CGA - Color Graphics Adapter | 1981 | 80×25 | 640×200 / 4 | 16 KB |
| HCC - Hercules Graphics Card | 1982 | 80×25 | 720×348 / 2 | 64 KB |
| PGA - Professional Graphics Controller | 1984 | 80×25 | 640×480 / 256 | 320 KB |
| EGA - Enhanced Graphics Adapter | 1984 | 80×25 | 640×350 / 16 | 256 KB |
| IBM 8514/8514 | 1987 | 80×25 | 1024×768 / 256 | - |
| MCGA - IBM Multicolor Graphics Adapter | 1987 | 80×25 | 320×200 / 256 | - |
| VGA - Video Graphics Array | 1987 | 80×25 | 640×480 / 16 | 256 KB |
| SVGA - Super Video Graphics Array (VESA BIOS Extensions/VBE 1.x) | 1989 | 80×25 | 800×600 / 256 | 512 KB |
| 640×480+ / 256+ | 512 KB+ | |||
| XGA | 1990 | 80×25 | 1024×768 / 256 | 1 MB |
| XGA/XGA-2 | 1992 | 80×25 | 1024×768 / 65,536 | 2 MB |
| SVGA - Super Video Graphics Array/SVGA (VESA BIOS Extensions/VBE 3.0) | 1998 | 132×60 | 1280×1024 / 16.7M | - |
VGA cards were widely accepted which determined some companies like ATI, Cirrus Logic and S3 to improve video cards resolution and the number of colors. So the Super VGA standard reached 2 MB of video memory and a resolution of 1024 x 768 in 256 colors mode.
In 1995 grew the number of 2D / 3D video adapter users. These cards were developed by Matrox, Creative, S3, ATI and others. In 1997 3dfx launched a video card called Voodoo more powerful than any other card on the market by inserting some 3D effects like MIP mapping, Z-buffering and anti-aliasing. After that card it followed others like Voodoo2, TNT and TNT2 from NVIDIA. The requested bandwidth was closed to PCI bus capacity. So Intel developed AGP (Accelerated Graphics Port) solving the strangulation between processors and the video card.
Video card components
A modern video card is formed by a card of printed circuit on which are disposed the rest of the components.
GPU - Graphics processing unit
The graphic processing unit is the dedicated processor optimized for graphic acceleration, especially designed to display 3D images. The main attributes of GPU are the core frequency usually between 250 MHz and 4 GHz and the number of paths (vertex and shaders) transposing a 3D image characterized bu lines and columns into a 2D image formed by pixels.
Video card BIOS
BIOS or firmware is the base program, usually hidden; It regulates the video card operations and offers instructions allowing the computer and software to interact with the video card. It's possible to contain information regarding the memory calendar, operating speeds and source voltages for the graphic processor, RAM memory and others.
Video memory
The memory capacity of modern video cards varies from 128 MB to 4 GB. There are used high speed memories or multiport memories like VRAM, WRAM, SGRAM, etc. Around 2003 video memories started to use the DDR technology so producers focused on DDR2, DDR3, GDDR3, GDDR4 and even GDDR5 used especially by ATI Radeon HD 4870.
| Memory type | Frequnecy (MHz) | Band width (GB/s) |
|---|---|---|
| DDR SDRAM/DDR | 166 - 950 | 1.2 - 30.4 |
| DDR2 SDRAM/DDR2 | 533 - 1000 | 8.5 - 16 |
| GDDR3 | 700 - 2400 | 5.6 - 156.6 |
| GDDR4 | 2000 - 3600 | 128 - 200 |
| GDDR5 | 3400 - 5600 | 130 - 230 |
Video card's outputs
Analogical adapter VGA (DE-15) it's a standard adapter adopted in the late 80s designed for CRT monitors also called a VGA connector. This standard has the following issues: electric noise, images distortion, etc.
Digital Visual Interface (DVI) it's a standard digital connector used for LCD, plasma, HD TVs and video projectors.
VIVO - Video In Video Out for S-Video, composite video and component video. It was inserted in order to allow TV connection, DVDs, video recorders and video games joysticks.
HDMI (High-Definition Multimedia Interface) - it's an advanced interface of audio / video connections launched in 2003, frequently used to connect game consoles to DVDs and to the monitor. The HDMI interface allows copy protection trough HDCP.
Cooling a video card
Video cards can use a lot of electric energy which is transformed in heat. If the heat is not dissipated the video card could overheat and deteriorate. To protect them there have been built cooling devices to transfer the heat somewhere else. There are usually used three kinds of cooling devices:
- Radiator: a device of passive cooling built from a metal that conducts the heat (usually aluminum or copper) away from the video card;
- Fan: an active cooling device. Used together with a radiator, the fan is more efficient;
- Water cooling: is a device built from a special radiator that uses water as cooling agent. This is the most efficient solution to cool down a video card.
