Understanding Video Cards and Monitors
Understanding Video Cards and Monitors
Alex Keller, Cody Whittington, Wayne Warren
TV input and output
Video cards must be compatible with the
buses or slots on the motherboard. Common
slot types used by video cards are:
◦ Current video cards typically use AGP and PCI
◦ Video cards in PCIe slots usually require 16x slots.
AGP video cards use either 4x or 8x slots.
◦ Older cards used PCI and VESA slots.
Some motherboards include a built-in video
card integrated on the Northbridge chip. This
video card is actually part of one of the buses
on the system (PCIe, AGP, or PCI).
The video card includes a connector for attaching
the monitor. Choose the video card with the
connector(s) you need
You can use special conversion plugs to convert
from one type of connector to another
Many video cards come with HDMI connectors for
connecting to a TV or a monitor.
If you purchase a video card with duel heads, you
can use duel monitors
Video cards include a processor (called a
graphics processing unit or GPU) that takes over
video rendering from the CPU, thereby increasing
◦ When selecting a video card, you have a wide choice of
video processors. Different processors might improve
◦ The use of this video processor is often referred to as
video hardware acceleration.
◦ Typically, settings in the operating system control how
much video processing is offloaded to the video card.
◦ Video cards also have a clock speed. Higher speeds
typically mean better performance.
For increased performance, especially in games,
you can install multiple video cards and link
those cards together so that multiple GPUs draw
a single screen.
◦ Scalable Link Interface (SLI) from nForce and CrossFire
from ATI are two different methods for linking video
◦ Cards are linked using a special bridge clip or through
software (depending on the implementation).
◦ The motherboard and the video cards must each support
the selected method (either SLI or CrossFire). The
motherboard must have multiple 16x PCIe slots.
◦ In most cases you will need to install identical video
cards, or at least video cards with very similar
Video cards have built-in memory. The amount
of memory on the card effects performance as
well as other characteristics of the display.
◦ The amount of memory ranges from 32 MB up to 2 GB
◦ Onboard video cards (integrated on the motherboard)
use a portion of the system memory for video
◦ Newer video cards will use the following types of
DDR, DDR2, and DDR3 memory are similar to system
memory. This type of memory is cheaper and provides less
performance features than using special graphics memory.
GDDR2, GDDR3, and GDDR5 are DDR memory designed
specifically for graphics.
HDCP is a method for copy-protecting digital
media. The purpose of HDCP is to prevent the
interception and copying of protected data
streams as they are sent from a playback
device (such as a DVD player) to a display
device (such as an HD TV).
◦ When playing protected content from a PC, the DVD
player, video card, and monitor (or TV) must all
◦ If you plan on watching protected content on your
PC, or playing content from your PC to an external
TV, make sure the video card supports HDCP.
Some video cards include features that allow them to receive
video signals and output them to a TV source.
You can display the computer screen on a TV using the following
◦ Analog TVs use an S-video port for video input.
◦ Digital TVs use the HDMI port for input.
◦ Many newer TVs also include a DVI input, allowing you to connect to the
DVI port on your computer.
◦ You can also use an HDMI converter to convert a DVI connector to an HDMI
A TV tuner allows your video card to accept a cable TV input and
change channels from within the computer. TV tuners can
process one or more of the following signals:
◦ NTSC, PAL, and SECAM are analog TV signal standards. NTSC was used in
North America but is being phased out.
◦ ATSC signals are digital TV signals. When purchasing a new TV tuner,
make sure it supports ATSC.
Most TV tuners use an S-video, F-type, or RCA composite port
for video input.
HDMI used in home theater systems have audio
integrated with the video signal. If you connect
your video card to a monitor or an HD TV using
the HDMI port, only video content will be carried
on the HDMI cable. Some video cards allow you
to include audio with the video signal using one
of the following methods:
◦ With audio pass-through, an audio output cable is
connected to the video card. The video card combines
the audio signal with the video signal for HDMI output.
This option is often called HDTV out.
◦ A graphics card with an onboard audio processor can
decode and process audio and send it out the HDMI
port. This option is often referred to as onboard sound.
The quality of images and animations are determined by the following
characteristics of display. The capability of your display depends on
both the video card and the monitor support.
-The resolution is the number of pixels displayed on screen.
A higher resolution means that more information can be shown on the
screen at a time. Modern standards range from 1024 (horizontal) x 756
(vertical) to 2048 x 1536 or even higher.
-The color depth is the number of different colors that can be
displayed on the screen at a time. Color depth is expressed in bits (a
higher bit count increases the number of colors that can be displayed).
Common bit depths include:
-8-bit (256 possible colors)
-16-bit, also called high color (65,536 possible colors)
-24-bit, also called true color (16.7 million possible colors)
-32-bit, also called true color (16.7 million possible colors and alpha
The refresh rate is the number of times the entire screen repaints per
second. Refresh rates are measured in hertz. A refresh rate of 70 Hz or
lower may cause eye fatigue. A desirable range of refresh rate is 75 Hz
to 85 Hz. The refresh rate you use is dependent upon the rate
supported by the card as well as the monitor.
DirectX is a set of Microsoft API (Application Program
Interface) that improves graphic, animation and
DirectX includes multiple components targeted to a
different aspect of multimedia. For example, Direct3D
is the 3D rendering component of DirectX.
Applications (typically games) are written using
features included in specific DirectX versions.
To view content written to a specific DirectX version,
your video card must also support that (or a higher)
OpenGL is an alternative standard to DirectX that is
used by some applications. Video cards support both
DirectX and OpenGL.
Video cards must be compatible with the buses or slots on
the motherboard. Common slot types used by video cards
Current video cards typically use AGP and PCI express slots.
Video cards in PCIe slots usually require 16x slots. AGP video cards use
either 4x or 8x
Select the video card based on the graphics processor type and
speed, the amount and type of video memory, as well as the
supported resolution and color depth.
Many newer PCI Express cards require a special 6-pin or
8-pin power connector. Be sure to connect the power after
inserting the card in the system and prior to turning the
If the motherboard has onboard video, disable the
onboard video in the BIOS when installing a card in the bus
CRT ( Cathode Ray Tube )
LCD ( Liquid Crystal Display )
A cathode ray tube monitor works by
illuminating millions of tiny red, blue and
green phosphor dots with a beam of
A cathode ray tube behind the monitor's
screen contains a filament that's held in a
While it is possible for a CRT monitor to have
a digital connection, virtually all CRT
monitors connect to the video card using a
DB-15 (also called a D-sub) connector.
LCDs are flat panels
that use a liquid
crystal material and
transistors to display
images. TFT (thin film
transistor) and active
matrix are additional
terms that are often
used to describe LCD
◦ Contrast ratio - refers to the difference in light
intensity between the brightest white and the
◦ Response time - indicates how quickly a pixel can
go from black, to white, and back to black.
Indicated in milliseconds
◦ Pixel pitch - the distance between pixels. A lower
number means a sharper image and possibly higher
Twisted Nematic Panels - most common type used
in computer monitors, especially in smaller sizes.
TN panels have very good response times (2ms to
5ms), so are well-suited for games with a lot of
Vertical Alignment Panels offer the best contrast
ratios of the display types, and are well suited for
movies that require good contrast.
In Plane Switching panels have the best color
reproduction quality and viewing angles of the
display types, and are well suited for graphic
design where full and accurate color representation
An LED (Light-Emitting Diode) based monitor is a special
type of LCD monitor. It still uses a liquid crystal display to
create images on the screen. However, it uses a different
type of backlight than that used in a standard LCD.
Traditional LCD monitors use cold cathode florescent
(CCFL) tubes to illuminate the display. LED monitors
replace the CCFL tubes with LED backlight technology.LED
monitors can display more colors more accurately than
standard LCD monitors.
LED monitors can be manufactured using smaller, thinner
LEDs use DC power, eliminating the need for an inverter.
LED monitors typically consume much less electricity than
LED backlights don't contain mercury, as CCFLs do.
Plasma monitors function using a
completely different technology as
compared to LCD and LED monitors.
Plasma displays utilize small cells that
contain electrically-charged ionized
gases. A plasma panel is made up of
millions of these cells sandwiched
between two panels of glass.
When electrical current is applied to a
plasma cell, the gas within the cell
forms a plasma and emits a photon of
light Each photon strikes a phosphor
painted on the inside of the cell,
allowing different colors to be
displayed. Each pixel in a plasma
display is made up of three cells; red,
green, and blue.
◦ For normal computing purposes, both provide a
sharp, clear display.
◦ Plasmas typically shine when watching Blu-Ray
movies or playing high definition games. They tend
to have less picture lag and sharper color resolution
than LCD displays.
◦ LCD monitors tend to be rated for 60,000 + hours of use
◦ Plasma monitors are usually rated between 20,000 –
◦ LCD screens typically have more pixels per square inch
than plasmas, making them more ideal for working with
complex spreadsheet programs or editing software.
◦ LCD displays tend to use much less power than plasma
displays, due to the fact that plasma screens have self
More than one monitor can be attached to the
same device. Each display can operate in two
◦ Extend – extends your desktop across both
monitors. Useful for creating more desktop space
◦ Mirror – when both monitors are showing the same
screen. Useful for giving presentations
◦ The D-sub connector, sometimes called a VGA
connector, uses a DB-15 connector with three
rows of pins. The D-sub connector on a video
card provides analog output. You can connect
the following monitors to a video card with a Dsub connector. Typically used with an analog
CRT monitor, but some LCD monitors also have
analog ports as well.
A DVI-D (digital video-digital) connection on a video card
provides digital output. DVI-D connections are rated as either
single link or dual link:
◦ Single link connectors have 3 rows of 6 pins with one
additional larger horizontal pin. Single link can support 60 Hz
up to 1920x1080 resolution.
◦ Dual link connectors have 3 rows of 8 pins plus the horizontal
pin (often called a 25-pin, 24+1-pin, or 24-pin connector).
Dual link can support 60 Hz up to 2048x1536 resolution.
◦ Dual link allows for longer cable lengths and a higher video
resolution. When choosing a video card, choose a card that
supports dual link whenever possible.
◦ You can only connect a digital monitor to a DVI-D connector.
High-Definition Multimedia Interface (HDMI) is a digital
video and audio connector used for high-definition digital
audio and video. HDMI combines the audio and video
signals onto a single cable. You might use HDMI
connectors in the following configurations:
◦ You can use a DVI-to-HDMI cable to connect the DVI-D output
from a video card to a monitor or an HDTV device that has an
HDMI connector. However, this configuration only supplies video,
and not audio, to the display device.
◦ You can purchase a video card with an HDMI connector. Many of
these video cards have an audio input port that accepts digital
audio into the video card where the audio signals are combined
with the video signals and sent out the HDMI port. In this
configuration, the video card does not process the audio, but
simply passes it through the video card from the external source
and onto the HDMI output.