Video card

A video card is an expansion card which generates
a feed of output images to a display. Within the industry, video cards are sometimes called
graphics add-in-boards, abbreviated as AIBs, with the word “graphics” usually omitted. History
Historically, video cards developed from the need to display graphics with growing higher
resolutions and colour depths on IBM PC compatible computers.
Standards such as MDA, CGA, HGC, Tandy, PGC, EGA, VGA, MCGA, 8514 or XGA were introduced
from 1982 to 1990 and supported by a variety of hardware manufacturers.
Virtually all current video cards are built with either AMD-sourced or Nvidia-sourced
graphics chips. 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. Dedicated vs integrated graphics As an alternative to the use of a video card,
video hardware can be integrated into the motherboard or the CPU. Both approaches can
be called integrated graphics. Motherboard-based implementations are sometimes called “on-board
video” while CPU-based implementations are called accelerated processing units. Almost
all desktop computer motherboards with integrated graphics allow the disabling of the integrated
graphics chip in BIOS, and have a PCI, or PCI Express slot for adding a higher-performance
graphics card in place of the integrated graphics. The ability to disable the integrated graphics
sometimes also allows the continued use of a motherboard on which the on-board video
has failed. Sometimes both the integrated graphics and a dedicated graphics card can
be used simultaneously to feed separate displays. The main advantages of integrated graphics
include cost, compactness, simplicity and low energy consumption. The performance disadvantage
of integrated graphics arises because the graphics processor shares system resources
with the CPU. A dedicated graphics card has its own random access memory, its own cooling
system, and dedicated power regulators, with all components designed specifically for processing
video images. Upgrading to a dedicated graphics card offloads work from the CPU and system
RAM, so not only will graphics processing be faster, but the computer’s overall performance
may also improve. Both of the dominant CPU makers, AMD and Intel,
are moving to APUs. One of the reasons is that graphics processors are powerful parallel
processors, and placing them on the CPU die allows their parallel processing ability to
be harnessed for various computing tasks in addition to graphics processing. APUs are
the newer integrated graphics technology and, as costs decline, will probably be used instead
of integrated graphics on the motherboard in most future low and mid-priced home and
business computers. As of late 2013, the best APUs provide graphics processing approaching
mid-range mobile video cards and are adequate for casual gaming. Users seeking the highest
video performance for gaming or other graphics-intensive uses should still choose computers with dedicated
graphics cards. Beyond the enthusiast segment is the market
for professional video cards for workstations used in the special effects industry, and
in fields such as design, analysis and scientific research. Nvidia is a major player in the
professional segment. In November, 2013, AMD introduced a so-called “Supercomputing” graphics
card “designed for data visualization in finance, oil exploration, aeronautics and automotive,
design and engineering, geophysics, life sciences, medicine and defense.”
Power demand 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. For example, the thermal design power for the
GeForce GTX TITAN is 250 Watts. 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 or eight-pin sockets that connect directly to the power
supply. While manufacturers of high-end video cards may recommend a minimum power supply
of 500 Watts in a computer, a power supply of at least 750 Watts is typical in a gaming
computer with a single high end video card. Providing adequate cooling becomes a challenge
in such computers. Computers with multiple video cards may need power supplies in the
1000W-1500W range. Heat extraction becomes a major design consideration for computers
with two or more high end video cards. Size
Video cards for desktop computers come in one of two size profiles, which can allow
a graphics card to be added even to small form factor PCs. Some video cards are not
of usual size, and are thus categorized as being low profile. Video card profiles are
based on width only, with low-profile cards taking up less than the width of a PCIe slot.
Length and thickness can vary greatly, with high-end cards usually occupying two or three
expansion slots, and with dual-GPU cards -such as the Nvidia GeForce GTX 690- generally exceeding
10″ in length. Multi-card scaling
Some graphics cards can be linked together to allow scaling of the graphics processing
across multiple cards. This is done using either the PCIe bus on the motherboard, or,
more commonly, a data bridge. Generally, the cards must be of the same model to be linked,
and most low power cards are not able to be linked in this way. AMD and Nvidia both have
proprietary methods of scaling, CrossfireX for AMD, and SLI for Nvidia. Cards from different
chipset manufacturers, architectures cannot be used together for multi card scaling. If
a graphics card has different sizes of memory, the lowest value will be used, with the higher
values being disregarded. Currently, scaling on consumer grade cards can be done using
up to four cards. Device drivers
The device driver usually supports one or multiple Application programming interfaces
like OpenGL, Direct3D, or Mantle, and the architecture of a GPU-family. A device driver
has to be specifically written for an operating system.
Industry The primary suppliers of the GPUs used in
video cards are AMD and Nvidia. In the third quarter of 2013, AMD had a 35.5% market share
while Nvidia had a 64.5% market share, according to Jon Peddie Research. In economics, this
industry structure is termed a duopoly. AMD and Nvidia also build and sell video cards,
which are termed graphics add-in-board in the industry. In addition to marketing their
own video cards, AMD and Nvidia sell their GPUs to authorized AIB suppliers, which AMD
and Nvidia refer to as “partners”. The fact that Nvidia and AMD compete directly with
their customer/partners complicates relationships in the industry. The fact that AMD and Intel
are direct competitors in the CPU industry is also noteworthy, since AMD-based video
cards may be used in computers with Intel CPUs. Intel’s move to APUs may weaken AMD,
which until now has derived a significant portion of its revenue from graphics components.
As of the second quarter of 2013, there were 52 AIB suppliers. These AIB suppliers may
market video cards under their own brands, and/or produce video cards for private label
brands and/or produce video cards for computer manufacturers. Some AIB suppliers such as
MSI build both AMD-based and Nvidia-based video cards. Others, such as EVGA, build only
Nvidia-based video cards, while XFX, now builds only AMD-based video cards. Several AIB suppliers
are also motherboard suppliers. The largest AIB suppliers, based on global retail market
share for graphics cards, include Taiwan-based Palit Microsystems, Hong Kong-based PC Partner,
Taiwan-based computer-maker Asustek Computer, Taiwan-based Micro-Star International, Taiwan-based
Gigabyte Technology, Brea, California, USA-based EVGA and Ontario, California USA-based XFX.
Size of market and impact of accelerated processing units on video card sales
Video card shipments totaled 14.5 million units in the third quarter of 2013, a 17%
fall from Q3 2012 levels. The traditional PC market is shrinking as tablet computers
and smartphones gain share. Years ago, the move to integrated graphics on the motherboard
greatly reduced the market for low end video cards. Now, AMD and Intel’s accelerated processing
units, which combine graphics processing with CPU functions on the CPU die itself, are putting
further pressure on video card sales. AMD introduced a line of combined processors which
it calls the AMD A-Series APU Processors while Intel, rather than marketing an exclusive
line of APUs, introduced its “4th Generation Intel® Core™ Processors”, some of which
are APUs. Those processors are described as offering “Superb visuals and graphics performance–without
the cost of a separate graphics card.” They are branded as having Intel HD Graphics or
Intel Iris Pro Graphics. As an example, the Intel Core i7 4750HQ with Iris Pro Graphics
5200, an accelerated processing unit for notebook computers, allows users with mid-range graphics
requirements to use a notebook computer without a video card. In a September, 2013 review
of the Intel Core i7 4750HQ accelerated processing unit the website stated: “With
its latest generation of integrated graphics, Intel set out to rival the performance of
the mid-range mobile Nvidia GeForce GT 650M graphics card. And the tests leave no doubt
about it, both 3DMark and the gaming benchmarks confirm that the [Intel] Iris Pro Graphics
5200 is on the same level of or slightly below that of the GT 650M.” Although the review
notes that Intel’s accelerated processing unit is not yet cost competitive, the technology
is approaching competitiveness, at least with mid-range mobile dedicated video. With anticipated
price reductions, it is predicted that APUs will eventually replace low to mid-range dedicated
video implementations. That will leave only the high-end enthusiast and professional market
segments for video card vendors. Parts A modern video card consists of a printed
circuit board on which the components are mounted. These include:
Graphics Processing Unit A graphics processing unit, also occasionally
called visual processing unit, is a specialized electronic circuit designed to rapidly manipulate
and alter memory to accelerate the building of images in a frame buffer intended for output
to a display. A video card is also a computer unto itself.
Heat sink A heat sink is mounted on most modern graphics
cards. A heat sink spreads out the heat produced by the graphics processing unit evenly throughout
the heat sink and unit itself. The heat sink commonly has a fan mounted as well to cool
the heat sink and the graphics processing unit. Not all cards have heat sinks, for example,
some cards are liquid cooled, and instead have a waterblock; additionally, cards from
the 1980s and early 1990s did not produce much heat, and did not require heatsinks.
Video BIOS The video BIOS or firmware contains a minimal
program for initial set up and control of the video card. It may contain information
on the memory timing, operating speeds and voltages of the graphics processor, RAM, and
other details which can sometimes be changed. The usual reason for doing this is to overclock
the video card to allow faster video processing speeds, however, this has the potential to
irreversibly damage the card with the possibility of cascaded damage to the motherboard.
The modern Video BIOS does not support all the functions of the video card, being only
sufficient to identify and initialize the card to display one of a few frame buffer
or text display modes. It does not support YUV to RGB translation, video scaling, pixel
copying, compositing or any of the multitude of other 2D and 3D features of the video card.
Video memory 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 1 GHz and 7 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. RAMDAC
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 Cathode ray tube
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. 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 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.
Output interfaces The most common connection systems between
the video card and the computer display are: Video Graphics Array Also known as D-sub, VGA 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
in evaluating pixels. Today, the VGA analog interface is used for high definition video
including 1080p and higher. While the VGA transmission bandwidth is high enough to support
even higher resolution playback, there can be picture quality degradation depending on
cable quality and length. How discernible this quality difference is depends on the
individual’s eyesight and the display; when using a DVI or HDMI connection, especially
on larger sized LCD/LED monitors or TVs, quality degradation, if present, is prominently visible.
Blu-ray playback at 1080p is possible via the VGA analog interface, if Image Constraint
Token is not enabled on the Blu-ray disc. Digital Visual Interface Digital-based standard designed for displays
such as flat-panel 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 standard RGB signal output to an old CRT or LCD monitor
with VGA input. Video In Video Out 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,
or 6 connectors. High-Definition Multimedia Interface HDMI is a compact audio/video interface for
transferring uncompressed video data and compressed/uncompressed digital audio data from an HDMI-compliant
device to a compatible digital audio device, computer monitor, video projector, or digital
television. HDMI is a digital replacement for existing analog video standards. HDMI
supports copy protection through HDCP. DisplayPort DisplayPort is a digital display interface
developed by the Video Electronics Standards Association. The interface is primarily used
to connect a video source to a display device such as a computer monitor, though it can
also be used to transmit audio, USB, and other forms of data. The VESA specification is royalty-free.
VESA designed it to replace VGA, DVI, and LVDS. Backward compatibility to VGA and DVI
by using adapter dongles enables consumers to use DisplayPort fitted video sources without
replacing existing display devices. Although DisplayPort has much of the same functionality
as HDMI, it is expected to complement the interface, not replace it.
Other types of connection systems Motherboard interfaces 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 manual adjustments required with jumpers.
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 bits 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. See also ATI – Alternative
AMD, NVIDIA – duopoly of 3D chip GPU and graphics card designers
Computer display standards – a detailed list of standards like SVGA, WXGA, WUXGA, etc.
Diamond Multimedia – Alternative Feature connector
GeForce, Radeon – examples of video cards GPGPU
Free and open-source device drivers: graphics – about the available FOSS device drivers
for graphic chips Mesa 3D – a free and open-source implementation
of rendering APIs Framebuffer – the computer memory used to
store a screen image Hercules – Monochrome
Mini-DIN connector List of video card manufacturers
Texture mapping – a means of adding image details to a 3D scene
Video In Video Out Z-buffering – a means of determining visibility
References External links
How Graphics Cards Work at HowStuffWorks Large image of graphic card history tree

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