Specifications

3D Graphics Accelerators
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Single- Versus Multiple-Pass Rendering
Various video card makers handle application of these advanced rendering techniques differently. The
current trend is toward applying the filters and basic rendering in a single pass rather than multiple
passes. Video cards with single-pass rendering and filtering typically provide higher frame-rate perfor-
mance in 3D-animated applications and avoid the problems of visible artifacts caused by errors in mul-
tiple floating-point calculations during the rendering process.
Hardware Acceleration Versus Software Acceleration
Compared to software-only rendering, hardware-accelerated rendering provides faster animation. Although
most software rendering would create more accurate and better-looking images, software rendering is too
slow. Using special drivers, these 3D adapters can take over the intensive calculations needed to render a
3D image that software running on the system processor formerly performed. This is particularly useful if
you are creating your own 3D images and animation, but it is also a great enhancement to the many mod-
ern games that rely extensively on 3D effects. Note that motherboard-integrated video solutions, such as
those listed in Tables 15.8 and 15.9, typically have significantly lower 3D performance than even low-end
GPUs because they use the CPU for more of the 3D rendering than 3D video adapter chipsets do.
To achieve greater performance, many of the latest 3D accelerators run their accelerator chips at very
high speeds, and some even allow overclocking of the default RAMDAC frequencies. Just as CPUs at
high speeds produce a lot of heat, so do high-speed video accelerators. Both the chipset and the mem-
ory are heat sources, so most mid-range and high-end 3D accelerator cards feature a fan to cool the
chipset. Also, most current high-end 3D accelerators use finned passive heatsinks to cool the memory
chips and make overclocking the video card easier (refer to Figure 15.11).
Software Optimization
It’s important to realize that the presence of an advanced 3D-rendering feature on any given video card is
meaningless unless game and application software designers optimize their software to take advantage of
the feature. Although various 3D standards exist (OpenGLand DirectX), video card makers provide drivers
that make their games play with the leading standards. Because some cards do play better with certain
games, you should read the reviews in publications such as Maximum PC to see how your favorite graphics
card performs with them. It’s important to note that, even though the latest video cards based on recent
ATI and NVIDIA chips support DirectX 9.x, many games still support only DirectX 8.x. As with previous
3D features, it takes time for the latest hardware features to be supported by game vendors.
Some video cards allow you to perform additional optimization by adjusting settings for OpenGL,
Direct 3D, RAMDAC, and bus clock speeds, as well as other options. Note that the bare-bones 3D
graphics card drivers provided as part of Microsoft Windows usually don’t provide these dialog boxes.
Be sure to use the drivers provided with the graphics card or download updated versions from the
graphics card vendor’s Web site. Although you can sometimes use generic drivers provided by the GPU
vendor, you should use drivers that have been specifically developed for your card to ensure that your
card’s particular features are fully supported.
Note
If you want to enjoy the features of your newest 3D card immediately, be sure to purchase the individual retail-packaged
version of the card from a hardware vendor. These packages typically come with a sampling of games (full and demo ver-
sions) designed or compiled to take advantage of the card with which they’re sold. The lower-cost OEM or “white box”
versions of video cards are sold without bundled software, come only with driver software, and might differ in other ways
from the retail advertised product. Some even use modified drivers, use slower memory or RAMDAC components, or lack
special TV-out or other features. Some 3D card makers use different names for their OEM versions to minimize confusion,
but others don’t. Also, some card makers sell their cards in bulk packs, which are intended for upgrading a large organiza-
tion with its own support staff. These cards might lack individual documentation or driver CDs and also might lack some of
the advanced hardware features found on individual retail-pack video cards.
Chapter 15
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