A video card, Graphics Card, or Graphics adapter is an expansion card which generates output images to a display.  Video hardware is often integrated into the motherboard, however all modern motherboards provide expansion ports to which a video card can be attached.

Modern low-end to mid-range motherboards often include a graphics chipset.  This graphics chipset usually has a small quantity of embedded memory and takes some of the system’s main RAM, reducing the total RAM available. This is usually called integrated graphics or on-board graphics, and is low-performance and undesirable for those wishing to run 3D applications. A dedicated graphics card on the other hand has its own RAM and Processor specifically for processing video images, and thus offloads this work from the CPU and system RAM. Almost all of these motherboards allow the disabling of the integrated graphics chip in BIOS, and have an AGP, PCI, or PCI Express slot for adding a higher-performance graphics card in place of the integrated graphics.

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


A GPU is a dedicated processor optimized for accelerating graphics. The processor is designed specifically to perform floating-point calculations, which are fundamental to 3D graphics rendering and 2D picture drawing. The main attributes of the GPU are the core clock frequency, which typically ranges from 250 MHz to 4 GHz 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.

The video BIOS or firmware contains the basic program, which is usually hidden, that governs the video card’s operations and provides the instructions that allow the computer and software to interact with the card.

The memory capacity of most modern video cards ranges from 128 MB to 8 GB.  The effective memory clock rate in modern cards is generally between 400 MHz and 3.8 GHz.

The RAMDAC, or Random Access Memory Digital-to-Analog Converter, converts digital signals to analog signals for use by a computer display that uses analog inputs such as CRT displays. The RAMDAC is a kind of RAM chip that regulates the functioning of the graphics card. 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.

VGA or Video Graphics adapter is an 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.

DVI or Digital Visual Interface is a Digital-based standard designed for displays such as flat-panel displays (LCDs, plasma screens, wide high-definition television displays) and video projectors.

Video In Video Out (VIVO) for S-Video, Composite video and Component video is Included to allow the connection with televisions, DVD players, video recorders and video game consoles. They often come in two 10-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).

High-Definition Multimedia Interface (HDMI) is an advanced digital audio/video interconnect released in 2003 and is commonly used to connect game consoles and DVD players to a display.

DisplayPort is an advanced license- and royalty-free digital audio/video interconnect released in 2007. DisplayPort intends to replace VGA and DVI for connecting a display to a computer.

Composite video is an analog system with lower resolution; it uses the RCA connector.

Component video has three cables, each with RCA connector (YCBCR for digital component, or YPBPR for analog component); it is used in projectors, DVD players and some televisions.

DB13W3 is an analog standard once used by Sun Microsystems, SGI and IBM.

DMS-59 is a connector that provides two DVI or VGA outputs on a single connector. This is a DMS-59 port.

Motherboard interface

* S-100 bus: designed in 1974 as a part of the Altair 8800, it was the first industry-standard bus for the microcomputer industry.

* ISA: Introduced in 1981 by IBM, it became dominant in the marketplace in the 1980s. It was an 8 or 16-bit bus clocked at 8 MHz.

* NuBus: Used in Macintosh II, it was a 32-bit bus with an average bandwidth of 10 to 20 MB/s.

* MCA: Introduced in 1987 by IBM it was a 32-bit bus clocked at 10 MHz.

* EISA: Released in 1988 to compete with IBM’s MCA, it was compatible with the earlier ISA bus. It was a 32-bit bus clocked at 8.33 MHz.

* VLB: An extension of ISA, it was a 32-bit bus clocked at 33 MHz.

* PCI: Replaced the EISA, ISA, MCA and VESA buses from 1993 onwards. PCI allowed dynamic connectivity between devices, avoiding the jumpers manual adjustments. It is a 32-bit bus clocked 33 MHz.

* UPA: An interconnect bus architecture introduced by Sun Microsystems in 1995. It had a 64-bit bus clocked at 67 or 83 MHz.

* USB: Although mostly used for miscellaneous devices, such as secondary storage devices and toys, USB displays and display adapters exist.

* AGP: First used in 1997, it is a dedicated-to-graphics bus. It is a 32-bit bus clocked at 66 MHz.

* PCI-X: An extension of the PCI bus, it was introduced in 1998. It improves upon PCI by extending the width of bus to 64-bit and the clock frequency to up to 133 MHz.

* PCI Express: Abbreviated PCIe, it is a point to point interface released in 2004. In 2006 provided double the data-transfer rate of AGP. It should not be confused with PCI-X, an enhanced version of the original PCI specification.

Video cards may use a lot of electricity, which is converted into heat. If the heat isn’t dissipated, the video card could overheat and be damaged. Cooling devices are incorporated to transfer the heat elsewhere. Three types of cooling devices are commonly used on video cards:

* Heat sink: a heat sink is a passive-cooling device. It conducts heat away from the graphics card’s core, or memory, by using a heat-conductive metal (most commonly aluminum or copper); sometimes in combination with heat pipes.

* Computer fan: an example of an active-cooling part. It is usually used with a heat sink.

* Water block: a water block is a heat sink suited to use water instead of air. It is mounted on the graphics processor and has a hollow inside. Water is pumped through the water block, transferring the heat into the water, which is then usually cooled in a radiator.

As the processing power of video cards has increased, so has their demand for electrical power. Current high-performance video cards tend to consume a great deal of power. While CPU and power supply makers have recently moved toward higher efficiency, power demands of GPUs have continued to rise, so the video card may be the biggest electricity user in a computer.  Although power supplies are increasing their power too, the bottleneck is due to the PCI-Express connection, which is limited to supplying 75 Watts.  Modern video cards with a power consumption over 75 Watts usually include a combination of six-pin (75W) or eight-pin (150W) sockets that connect directly to the power supply

You need to ensure that the type of the video card corresponds to the type of slot on your motherboard. The major types are PCI Express, PCI, and AGP, and each has a slot type of the same name.

If you are buying a video card, it is important to know which type of slot you have and if the video card is compatible with your Operating System.

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
NUBUS 32 10 10-40 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 66 528 Parallel
AGP 4x 32 66 1000 Parallel
AGP 8x 32 66 2000 Parallel
PCIe x1 1 2500 / 5000 250 / 500 Serial
PCIe x4 1 × 4 2500 / 5000 1000 / 2000 Serial
PCIe x8 1 × 8 2500 / 5000 2000 / 4000 Serial
PCIe x16 1 × 16 2500 / 5000 4000 / 8000 Serial
PCIe x16 2.0 1 × 16 5000 / 10000 8000 / 16000 Serial

* Albatron (Legacy PCI)
* AOpen
* Asus
* Buffalo Inc.
* Biostar
* Chaintech
* Club 3D
* Colorful
* Connect Components Ltd.
* Diamond Multimedia
* Digital Alliance
* Eagle
* ELSA Technology Inc
* EPoX
* Foxconn
* Gainward
* Galaxy Technology
* Gecube
* Gigabyte
* GraphicTech
* Hercules Guillemot
* HighTech Information System (HIS)
* Info-Tek Corp.
* Inno3D
* Jaton Corporation
* Jetway
* Leadtek
* Manli
* Matrox
* Palit
* Pixel View
* Point of View
* PowerColor
* RedFox
* S3 Graphics
* Sapphire Technology
* Sensoray
* TYAN Computer
* Transcend
* Triplex REDai
* Tul / PowerColor Corporation
* Universal abit
* Vaikoo
* Viking Interworks
* VisionTek
* Wistron Corporation
* Xinhua Graphics
* Zotac

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