When
the time comes to upgrade a computer, graphics cards are frequently
overlooked. But few components can provide both the performance boost
and visible improvement that a good graphics card can. If you have an
older computer, or are a gamer who demands perfection, the quality and
advanced features that the latest graphics cards are guaranteed to
impress.
Editor's Choice
There are many considerations when it comes to buying a graphics card.
Depending on your budget, whether you are a games freak, what size
monitor you have, how new your PC is, whether you are interested in
video editing--a different graphics card will be the right choice. We'll
be going on to discuss in depth all these features, but if you're just
itching to buy a card now and want a recommendation you can trust, just
pick from the list which definition best fits your needs and you'll be
taken to a graphics card that will suit you. Don't forget to check the
products technical data before you buy, to ensure that the card is
compatible with your system.
Which Graphics card do I need?
I want the fastest graphics card for games that money can buy
I want to play the latest games and have under £200 to spend
I want to play games, but I have about £100 to spend
I want a card with video out, which is great at playing the latest games
I want a graphics card that has a TV tuner included with it
Overview
Graphics accelerator cards are advancing in speed and supported features
faster than nearly any other PC component. The latest cards have more
dedicated video memory than the total memory in an entry-level computer,
as well as processors that rival the performance of CPUs on many desktop
PCs. Some graphics cards have features like video input ports and TV
tuner capabilities that make them useful for editing video or watching
television on a computer display. Others let users watch high-quality
full-screen DVD movies without any special decoding hardware between the
DVD-ROM player and the graphics card. The most dramatic advances are
happening in the field of 3-D acceleration, allowing for game graphics
that are increasingly detailed and realistic. Best of all, so many
graphics cards are available that it isn't difficult to find one that
perfectly matches your needs and budget.
When shopping for a graphics card, keep your monitor's specifications
handy. You'll need to know your monitor's maximum resolution, maximum
refresh rate, and the resolution you use for day-to-day work. It also
helps to decide if you need a card with advanced 3-D acceleration
capabilities (for gaming or designing Web graphics) or simply a better
card for 2-D applications (for average business use). It's possible to
save money by buying a good 2-D card with minimal 3-D acceleration
features.
2-D Acceleration
All graphics cards have 2-D acceleration capabilities. This is sometimes
called Windows acceleration, as Windows is a 2-D operating system that's
used mainly to run 2-D applications. Of course, true 3-D is impossible
on a flat display, so 2-D actually refers to pre-rendered graphics while
3-D refers to the graphics card's ability to render graphics on the fly.
In practical terms, a graphics card's 2-D performance is measured by
the speed at which it handles tasks such as moving windows, scrolling
text, and displaying flat, pre-rendered images. A card with good 2-D
performance lets users perform all of these tasks smoothly, without any
stutters. A card with excellent 2-D performance executes these tasks
smoothly at high resolutions, refresh rates, and colour depths.
Practically any graphics card sold today with at least 8 MB of memory
offers excellent 2-D acceleration on 17-inch or smaller monitors. Those
with 19-inch or larger monitors will want a card with 16 to 32 MB of
memory.
Resolution
All graphics cards have a maximum resolution or limit to the number of
pixels they can render at once. The maximum resolution is listed in the
number of horizontal pixels by the number of vertical pixels (such as
1,280 x 1,024). If you have a 17-inch monitor, it's easy to find an
inexpensive graphics card to enhance your monitor's capabilities. If you
have a 19- or 20-inch monitor, you may need to spend more money for a
graphics card that complements the display.
Maximum possible resolution is a function of the amount of memory a
graphics card has, so keep that in mind when shopping around. Beware of
graphics cards that specify a high possible maximum resolution at a low
colour depth and refresh rate. Sure, they are capable of hitting high
resolutions, but if the screen is flickering and images can't use
millions of colours, these cards won't enhance your display.
Refresh Rate
Measured in hertz, the refresh rate is the number of times per second
that a monitor screen updates. Low refresh rates of 60 Hz or less can
cause perceptible flicker, as they are not fast enough to trick the eye
into thinking the display is a solid image. This is fatiguing to the
eyes and even causes headaches. When buying a graphics card, make
certain it supports a refresh rate of 75 Hz or higher at the maximum
resolutions and colour depths you plan to work with.
Colour Depth
The number of colours a display can create at once, measured in bits per
pixel (bpp), is known as colour depth. You can determine the maximum
number of possible colours by taking two to the power of the bit depth.
For example, when a graphics card is set to output 8-bit colour, each
pixel can display one of 256 total available colours (two to the eighth
power). The most common colour depths are 16-bit High Colour (over
65,000 possible simultaneous colours) and 24-bit True Colour (over 16.7
million possible simultaneous colours).
Buy a graphics card capable of displaying 24-bit colour or better
with the refresh rate set at a value of 75 Hz or faster and at the
maximum resolution you plan to work with. A colour output of 24 bits is
close enough to photographic quality that it greatly enhances image
editing, Web surfing, and nearly any other application. Some 3-D
accelerator cards can handle 24-bit or higher colour depths for 2-D
applications but can only support 16-bit colour for 3-D
programs--something to remember if you value 3-D colour quality over raw
performance.
3-D Acceleration
Every graphics card sold today comes with at least rudimentary 3-D
acceleration, and many are designed for maximum performance in this
area. Today's games use three major 3-D graphics application program
interfaces (APIs): Direct3D, OpenGL, and Glide. Nearly every card on the
market accelerates Direct3D and OpenGL graphics, but Glide is a
proprietary API owned by 3dfx Interactive, Inc., and only cards using a
3dfx chipset support it. There are few games developed solely for Glide
anymore, so don't hesitate to purchase a card that doesn't support Glide
if the rest of the feature set looks good.
Triangles Per
Second
Many graphics cards with 3-D accelerator capabilities have a
triangles-per-second value listed in the specifications. This is a
generic way to compare the performance of different cards. Current 3-D
engines used in consumer products, such as games, construct every object
with triangles of varying size. The more triangles the card can render
per second, the more complex 3-D scenes will appear. Cards that have a
high triangles-per-second value can display more objects or use more
triangles in the construction of existing objects, smoothing rough edges
and adding detail for a more realistic appearance. Currently there are
outstanding consumer-level 3-D cards available that can render 15
million or more triangles per second.
When you are comparing cards, make sure that the triangles-per-second
value refers to the number of plain triangles a card can render. Some
companies list the number of triangles per second with various filters,
textures, and other processor-hungry features applied, which can make
the number seem abnormally low.
RAMDAC
An important but often overlooked component of a graphics card is its
random access memory digital-to-analog converter (RAMDAC), sometimes
referred to merely as a DAC. This is the chip that converts the digital
information from the graphics card into an analog signal that a typical
monitor can understand. It is similar to the DAC in a CD player, which
converts a digital audio signal into an analog signal the speakers can
use.
The quality of the RAMDAC directly affects the quality of the output
you see on the monitor. Excellent RAMDACs help retain colour purity and
provide better image convergence than their low-quality counterparts.
The RAMDAC also determines the maximum refresh rates the graphics card
supports. RAMDAC speed is measured in megahertz, with higher speeds
corresponding to higher maximum refresh rates.
Memory
A graphics card's memory size helps determine the maximum resolution and
colour depth the card supports. Graphics cards with 8 MB of RAM
generally support 24-bit colour at resolutions of 1,280 x 1,024 to 1,600
x 1,200, while 16 MB cards can handle that same 24-bit colour depth all
the way up to 1,900 x 1,200. You'll want a card with 32 MB of memory or
more to get the most from the latest computer games, as high colour
depths in 3-D graphics require more memory. The speed of the memory has
also become a factor of late with the introduction of DDR (Double Data
Rate) memory. This is of most interest to gamers, as the memory
bandwidth is one of the limiting factors when it comes to rendering 3D
scenes fast. DDR memory adds a premium to the price you will pay, but if
gaming is a priority it's worth paying the extra.
The amount of video memory you need varies depending on the size of
your monitor and the applications you plan to use. Even the best 17-inch
monitors are practically unusable above a resolution of 1,280 x 1,024,
and most people set them at 1,024 x 768, so an 8 MB graphics card
provides plenty of power. You can use 19-inch and larger monitors at
resolutions of 1,600 x 1,200 or higher, so those with larger monitors
will want a graphics card with between 16 and 32 MB. Anyone who plans to
play the latest 3-D games will want to buy a card with the largest
amount of memory within their budget, regardless of the size of their
monitor.
Interface (PCI
versus AGP)
Graphics cards transfer so much information back and forth that it is
important they use a fast interface. Most graphics cards use either a
peripheral component interconnect (PCI) or accelerated graphics port (AGP)
interface. AGP is a newer, more advanced interface, created specifically
for graphics cards. Its transfer rates are two to eight times faster
than those of a PCI interface. AGP interfaces also offer improved
handling of textures and other graphics-related advantages.
We recommend using AGP products, but you'll have to make certain your
motherboard has an AGP slot. Check your computer's documentation to see
if it features an AGP port and verify that the port is available (not
integrated) by opening up your computer and looking for a short (usually
brown) card slot located near the power supply. You'll also want to see
if the AGP port you do have supports the 1x, 2x, or 4x AGP standard. The
1x AGP offers a maximum transfer rate of 266 MB per second, which is
twice as fast as a PCI interface. The 2x AGP standard runs at 533 MB per
second, and 4x AGP runs at 1.07 GB per second. Older AGP ports will not
take full advantage of 4x AGP cards, but should still work with them in
case you plan to transplant the graphics card into a 4x AGP-equipped
system later.
If you plan mainly to use the card for 2-D applications, such as word
processing and spreadsheet software, a PCI or 1x AGP card will get the
job done nicely while saving you some money. If you plan to play any 3-D
games, look for cards using the fastest AGP standard your motherboard
will support.
TV Features
Some graphics cards have external jacks that let users either send the
video signal to a standard television or accept a video signal from an
external device such as a VCR or camcorder. If video-out sounds
appealing, look for a card that can send a signal to a TV without
blanking the monitor screen in the process. If you need a card that
accepts video input, be sure it has the necessary software to make good
use of that signal. Some cards are packaged with software that lets you
watch TV, grab video stills, and even edit video input.
DVD Decoding
If you have a PC with a DVD-ROM drive but no decoding hardware, be aware
that not all graphics cards are good at decoding DVD signals. Sometimes
a card is just not designed for that task; other times a card won't work
because of bad software. If DVD decoding is an important feature to you,
look for a card specifically designed for enhanced DVD playback and make
sure it comes with all the software you'll need to view the DVD content.
Bundled Software
Many 3-D cards come with incredible bundles that feature full versions
of popular 3-D games. You never should buy a graphics card based solely
on the software it comes with, but if you were planning to buy the
software anyway, it sometimes makes sense to get some new hardware that
can take advantage of it.
Look closely at the titles bundled with a graphics card before
committing to a purchase. Often bundles include trial or hobbled demo
versions and require users to pay extra for the full release.
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