Information about Graphics Card

'''Video Card '''

Connects to: Motherboard via one of PCI AGP PCI Express Display via one of VGA connector Digital Visual Interface Composite video Component video HDMI DMS-59

A video card, also referred to as a graphics accelerator card, display adapter, graphics card, and numerous other terms, is an item of personal computer hardware whose function is to generate and output images to a display. It operates on similar principles as a sound card or other peripheral devices.

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. An integrated graphics controller may be referred to as an "integrated graphics processor" (IGP).

Some video cards offer added functionalities, such as video capture, TV tuner adapter, MPEG-2 and MPEG-4 decoding or even FireWire, mouse, light pen, joystick connectors, or even the ability to connect two monitors.

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.

History

Video cards’ history starts in the 1960s, when printers were replaced with screens as visualization element. Video cards were needed to create the first images.

	Year	Text Mode	Graphics Mode	Colors	Memory	Seventeen
MDA	1981	80*25	-	1	4 KB
CGA	1981	80*25	640*200	16	16 KB
HGC	1982	80*25	720*348	1	64 KB
EGA	1984	80*25	640*350	16	256 KB
IBM 8514	1987	80*25	1024*768	256	-
MCGA	1987	80*25	320*200	256	-
VGA	1987	720*400	640*480	256	256 KB
SVGA	1989	80*25	1024*768	256	17	2 MB
XGA	1990	80*25	1024*768	65,536	1 MB

The first video card, which was released with the first IBM PC, was developed by IBM in 1981. The MDA (Monochrome Display Adapter) could only work in text mode representing 25x80 lines in the screen. It had a 4KB video memory and just one color.^[1]

Starting with the MDA in 1981, several video cards were released, which are summarized in the attached table.^[2][3][4][5]

VGA was widely accepted, which lead some corporations such as ATI, Cirrus Logic and S3 to work with that video card, improving its resolution and the number of colours it used. And so was born the SVGA (Super VGA) standard, which reached 2MB of video memory and 1024 x 768 dots of resolution at 256 color mode.

The evolution of video cards took a turn for the better in 1995 with the release of the first 2D/3D cards, developed by Matrox, Creative, S3 and ATI, among others. Those video cards followed the SVGA standard, but incorporated 3D functions. In 1997, 3dfx released the graphics chip Voodoo, which was very powerful and included new 3D effects (Mip Mapping, Z-buffering, Anti-aliasing...). From this point, a series of 3D video card releases happened, like Voodoo2 from 3dfx, TNT and TNT2 from NVIDIA. The power reached with these cards exceeded the PCI port capacity. Intel developed the AGP (Accelerated Graphics Port) which solved the bottleneck between the microprocessor and the video card. From 1999 until 2002, NVIDIA controlled the video card market (taking over 3dfx)^[6] with the GeForce family. The improvements carried out in these years were focused in 3D algorithms and graphics processor clock rate. Nevertheless, video memory also needed to improve their data rate, and DDR technology was incorporated. The capacity of video memory goes in this period from 32 MB with GeForce to 128 MB with GeForce 4.

In 2006, the leadership of the video cards market^[7] was disputed between NVIDIA and ATI with their biggest selling models GeForce and Radeon respectively.

Components

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

Graphics processing unit (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 650 MHz in modern cards, 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.

Type	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

Video memory

If the video card is integrated in the motherboard, it will use the computer RAM memory (lower throughput). If it is not integrated, the video card will have its own video memory which is called Video RAM or VRAM. The VRAM capacity of most modern video cards range from 128 to 1024 MB (workstation graphics cards). In 2006, the VRAM was based on DDR technology, standing out DDR2, GDDR3 and GDDR4. The memory clock rate is between 400 MHz and 1.6 GHz. A very important element of the video memory is the Z-buffer, which manages the depth coordinates in 3D graphics.

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 (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.

RAMDAC

Random Access Memory Digital-to-Analog Converter. RAMDAC takes responsibility for turning the digital signals produced by the computer processor into an analog signal which can be understood by the computer display. Depending on the number of bits used and the RAMDAC data transfer rate, the converter will be able to support different computer display refresh rates. With CRT displays, it is best to work over 75 Hz and never under 60 Hz, in order to minimise flicker.^[8] (With LCD displays, flicker is not a problem.) Due to the growing popularity of digital computer displays and the migration of some of its functions to the motherboard, the RAMDAC is slowly disappearing. All current LCD and plasma displays and TVs work in the digital domain and do not require a RAMDAC. There are few remaining legacy displays which feature analog inputs (VGA, component, SCART etc) only; these do require a RAMDAC but they reconvert the analog signal back to digital before they can display it, with the unavoidable loss of quality stemming from this digital-to-analog-to-digital conversion.

Outputs

The most common connection systems between the video card and the computer display are:

• SVGA: Analog standard from the late 1980s, it was designed for CRT displays. Some problems of this standard are electrical noise, image distortion and sampling error evaluating pixels.
• DVI: Designed for digital displays such as LCDs, plasma screens and video projectors. It avoids image distortion and electrical noise, corresponding each pixel from the computer to a display pixel, using its native resolution.
• S-Video: Included to allow the connection with DVD players, video recorders and video game consoles.

Other connection systems are:

• Composite video: Analogic system, with very low resolution. It uses RCA connector.
• Component video: It has three cables, each with RCA connector (YCbCr); it is used in projectors.
• HDMI: digital technology released in 2003, whose goal is to replace all the others.

Bus	Width (bits)	Clock rate (MHz)	Bandwidth (MB/s)	Style
ISA XT	8	4,77	8	Parallel
ISA AT	16	8,33	16	Parallel
MCA	32	10	20	Parallel
EISA	32	8,33	32	Parallel
VESA	32	40	160	Parallel
PCI	32 - 64	33 - 100	132 - 800	Parallel
AGP 1x	32	66	264	Parallel
AGP 2x	32	133	528	Parallel
AGP 4x	32	266	1000	Parallel
AGP 8x	32	533	2000	Parallel
PCIe x1	1*32	25 / 50	100 / 200	Serial
PCIe x4	1*32	25 / 50	400 / 800	Serial
PCIe x8	1*32	25 / 50	800 / 1600	Serial
PCIe x16	1*32	25 / 50	1600 / 3200	Serial

Motherboard interface

Chronologically, connection systems between video card and motherboard were, mainly:

• ISA: 16 bits architecture, 8 MHz data transfer rate. Released in 1981 by IBM, dominant in the marketplace in the 1980s.
• MCA: 32 bits, 10 MHz. Released in 1987 by IBM. It wasn’t compatible with previous motherboards.
• EISA: 32 bits, 8.33 MHz. Released in 1988 to compete with IBM. Compatible with previous motherboards.
• VESA: ISA extension. 32 bit, 33 MHz.
• PCI: 32 bit, 33 MHz. Replaced the previous buses from 1993. PCI allowed dynamic connectivity between devices, avoiding the jumpers manual adjustments. PCI-X was a version that improved PCI to 64 bits and 133 MHz.
• AGP: Dedicated to graphics bus, 32 bits, 66 MHz.
• PCI-Express: Point to point interface, released in 2004. In 2006 provided double data transfer rate of AGP. Should not be confused with PCI-X, an enhanced version of the original PCI specification.

In the attached table^[9] is a comparison between a selection of the features of some of those interfaces.

Cooling devices

Due to video card work charge, high temperatures are reached, which can cause a breakdown. Cooling devices are incorporated to avoid excessive heat. There are two types of cooling devices, and both can be used at the same time:

• Heat sink: generally referred to as a passive cooling device, it has no moving parts and, therefore, is soundless and very reliable; it absorbs and dissipates heat from the GPU using thermal contact (by either direct or radiant contact with a cooling medium such as air). Its effectiveness depends on its size and other characteristics including shape and material (generally copper or aluminium).
• Computer fan: usually known as an active cooling device, it has moving parts to push hot air away from the video card and as such will generate a small amount of noise. It is more effective than a heat sink at cooling, but due to the moving parts is far less reliable than a passive heat-sink.
• Water Block (See: liquid cooling): uses liquid and heat sinks to cool the GPU. This method is used less often but is much more favorable to both other options as it is more effective than a fan and soundless just like a passive cooling device.
  

Power supply

Until 2006, video card power consumption had not been a big problem; nevertheless, present video card tendency is to consume even more power. Although power supplies are increasing their power too, the bottleneck is due to the PCI-Express connection, which is limited to supplying 150W.^[10] Nowadays, video cards with a power consumption over 150W usually include a six-pin power socket that connects directly to the power supply,^[11] which allows a direct connection between the computer power supply and the card, avoiding motherboard connection and, therefore, the PCIe port.

Manufacturers

Two types of manufacturers must be distinguished:

GPU and IGP Manufacturers

• Current GPU manufacturers:
• AMD (acquired ATI in 2006)
• NVIDIA
• Matrox
• Current IGP-only manufacturers:
• Intel
• VIA Technologies (acquired S3 Graphics in 2001)

Video Card Manufacturers

• Video card manufacturers: They assemble the GPU with the other components, causing differences between video cards with the same chip.

See also:

List of defunct graphics chips and card companies

Graphics APIs

Due to the difficulties working with video cards at a programming level, interfaces which abstract the complexity and diversity of the graphic card primitives appeared. The most important are:

• Direct3D: Released by Microsoft in 1996, is a component of DirectX. Designed to be used exclusively in Windows, it is used by the majority of Windows videogames. The latest version of DirectX is DirectX 10, although the majority of computers still rely on graphics cards that use DirectX 9.0c.
• OpenGL: Developed by Silicon Graphics in the early 1990s, OpenGL is a free, open, multi-language and multi-platform API. It is widely used in CAD, virtual reality, scientific visualization, information visualization, flight simulation and some games, particularly on Linux and other Unix like operating systems. The latest version is OpenGL 2.1.

Graphics techniques

Some of the most frequently used effects for enhancing the perceived quality of the output of graphics cards include the following:

• Anti-aliasing (AA): a technique used to counter distortion caused by aliasing effects.
• Shader: pixel and vertex processing in terms of illumination, atmospheric optical phenomena or multi-layer surfaces.
• High dynamic range rendering (HDR): a technique used to enable a wider range of brightness in real scenes (from light sources to dark shadows).
• Texture mapping: allows the addition of details on surfaces, without adding complexity.
• Motion blur: technique that blurs objects in motion.
• Depth of field: technique that blurs faraway objects.
• Lens flare: imitation of light sources.
• Fresnel effect: reflections over an object, depending on the angle of vision. The more angle of vision, the more reflection.
• Anisotropic filtering: enhances viewing angle of a displayed texture as it increases.

See also

• 3D computer graphics
• OpenGL – Cross-platform API.
• Direct3D – Microsoft’s DirectX API component.
• GeForce – Examples of GPUs.
• Z-buffering – Where depth coordinates are managed.
• List of manufacturers
• Graphics hardware and FOSS
• Scalable Link Interface
• ATI CrossFire

References

External links

• Jumper settings for Video Card
• Tom's Hardware: Video Card Benchmark Charts
• Some graphics techniques
• Graphics Beginners Guide
• How to install a graphics card
• How to repair a graphics card

Manufacturers

• ATI website
• Matrox website
• NVIDIA website