- Video card
Video Card image = Gpu-connections.png Connects to
Motherboard via one of:
Display via one of:
A video card, Graphics Card, or Graphics adapter is an expansion card which generates output images to a display. Most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors (multi-monitor). Other modern high performance video cards are used for more graphically demanding purposes, such as PC games.
Video hardware is often integrated into the motherboard, however all modern motherboards provide expansion ports to which a video card can be attached. In this configuration it is sometimes referred to as a video controller or graphics controller. Modern low-end to mid-range motherboards often include a graphics chipset manufactured by the developer of the northbridge (i.e. an nForce chipset with Nvidia graphics or an Intel chipset with Intel graphics) on the motherboard. This graphics chip 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.
- 1 Components
- 1.1 Graphics Processing Unit
- 1.2 Video BIOS
- 1.3 Video memory
- 1.4 RAMDAC
- 1.5 Outputs
- 1.6 Motherboard interface
- 1.7 Cooling devices
- 1.8 Power demand
- 2 Installation
- 3 References
- 4 External links
A modern video card consists of a printed circuit board on which the components are mounted. These include:
Graphics Processing Unit
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.
Modern GPUs are massively parallel, and fully programmable. Their computing power in orders of magnitude are higher than that of CPUs. As consequence, they challenge CPUs in high performance computing, and push leading manufacturers on processors.
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. It may contain information on the memory timing, operating speeds and voltages of the graphics processor, 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.
Type Memory clock rate (MHz) Bandwidth (GB/s) DDR 166 - 950 1.2 - 30.4 DDR2 533 - 1000 8.5 - 16 GDDR3 700 - 2400 5.6 - 156.6 GDDR4 2000 - 3600 128 - 200 GDDR5 900 - 5600 130 - 230
The memory capacity of most modern video cards ranges from 128 MB to 8 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 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, GDDR4 and GDDR5. The effective memory clock rate in modern cards is generally between 400 MHz and 3.8 GHz.
Video memory may be used for storing other data as well as the screen image, such as the Z-buffer, which manages the depth coordinates in 3D graphics, textures, vertex buffers, and compiled shader programs.
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. With CRT displays, it is best to work over 75 Hz and never under 60 Hz, in order to minimize flicker. (With LCD displays, flicker is not a problem.) Due to the growing popularity of digital computer displays and the integration of the RAMDAC onto the GPU die, it has mostly disappeared as a discrete component. All current LCDs, plasma displays and TVs work in the digital domain and do not require a RAMDAC. There are few remaining legacy LCD and plasma displays that feature analog inputs (VGA, component, SCART etc.) only. These 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.
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.
Digital Visual Interface (DVI)
Digital-based standard designed for displays such as flat-panel displays (LCDs, plasma screens, wide high-definition television displays) and video projectors. In some rare cases high end CRT monitors also use DVI. It avoids image distortion and electrical noise, corresponding each pixel from the computer to a display pixel, using its native resolution. It is worth to note that most manufacturers include DVI-I connector, allowing(via simple adapter) standard RGB signal output to an old CRT or LCD monitor with VGA input.
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 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)
An advanced digital audio/video interconnect released in 2003 and is commonly used to connect game consoles and DVD players to a display. HDMI supports copy protection through HDCP.
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.
Other types of connection systems
Composite video Analog system with lower resolution; it uses the RCA connector. Component video It 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 An analog standard once used by Sun Microsystems, SGI and IBM. DMS-59 A connector that provides two DVI or VGA outputs on a single connector. This is a DMS-59 port.
Chronologically, connection systems between video card and motherboard were, mainly:
- 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.
In the attached table is a comparison between a selection of the features of some of those interfaces.
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
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. It uses air (most common), or in extreme cooling situations, water (see water block), to remove the heat from the card. When air is used, a fan is often used to increase cooling effectiveness.
- Computer fan: an example of an active-cooling part. It is usually used with a heat sink. Due to the moving parts, a fan requires maintenance and possible replacement. The fan speed or actual fan can be changed for more efficient or quieter cooling.
- 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. This is the most effective cooling solution without extreme modification.
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. If you buy a video card which is the wrong slot then you can't install it on your computer. If you buy a video card not compatible with your Operating System your graphics or resolution may be impaired.
- ATI, NVIDIA - duopoly of 3D chip GPU and graphics card designers
- ATI Crossfire - ATI's proprietary mechanism for scaling graphics performance
- Computer display standards - detailed list of standards like SVGA, WXGA, WUXGA, etc.
- Feature connector
- GeForce, Radeon – Examples of GPUs.
- GPGPU (i.e.: CUDA, AMD FireStream)
- Graphics hardware and FOSS
- Framebuffer - The computer memory used to store a screen image
- Mini-DIN connector
- List of video card manufacturers
- Scalable Link Interface - NVIDIA's proprietary mechanism for scaling graphics performance
- Texture mapping - A means of adding image details to a 3D scene
- Video In Video Out (VIVO)
- Z-buffering – A means of determining visibility.
- ^ ATI FireGL V8650.
- ^ NVIDIA Quadro FX 5800.
- ^ "Refresh rate recommended". http://www.worldstart.com/tips/tips.php/1146.
- ^ "Buses features". http://en.wikipedia.org/wiki/List_of_device_bandwidths#Computer_buses.
- ^ http://www.xbitlabs.com/articles/video/display/power-noise.html X-bit labs: Faster, Quieter, Lower: Power Consumption and Noise Level of Contemporary Graphics Cards
- ^ http://www.codinghorror.com/blog/archives/000662.html Coding Horror Video Card Power Consumption
- ^ Maxim Integrated Products. "Power-Supply Management Solution for PCI Express x16 Graphics 150W-ATX Add-In Cards". http://www.maxim-ic.com/appnotes.cfm/an_pk/3605.
- Mueller, Scott (2005) Upgrading and Repairing PCs. 16th edition. Que Publishing. ISBN 0-7897-3173-8
- Graphics Card Comparisons, Performance, and Specifications
- How Graphics Cards Work at HowStuffWorks
Basic computer components Input devices Output devices Removable data storage Computer case Data ports
- 1 Components
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Look at other dictionaries:
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