Hardware Reference
In-Depth Information
Figure 12.1. A typical example of a mid-range video card optimized for dual-GPU gaming
(NVIDIA SLI) and HDTV support.
Virtually all video adapters on the market today use chipsets that include 3D acceleration features.
The following sections examine the video BIOS and processor in greater detail.
The Video BIOS
Video adapters include a BIOS that is separate from the main system BIOS. If you turn on your
monitor first and look quickly, you might see an identification banner for your adapter's video BIOS
at the beginning of the system startup process.
Similar to the system BIOS, the video adapter's BIOS takes the form of a read-only memory (ROM)
chip containing basic instructions that provide an interface between the video adapter hardware and
the software running on your system. The software that makes calls to the video BIOS can be a
standalone application, an operating system (OS), or the main system BIOS. The programming in the
BIOS chip enables your system to display information on the monitor during the system POST and
boot sequences, before any other software drivers have been loaded from disk.
See the
Chapter 5
section, “
BIOS Basics
,”
p.
263
.
In a few cases (mainly with high-performance gaming-oriented cards), the video BIOS also can be
upgraded, just like a system BIOS. The video BIOS normally uses a rewritable chip called an
electrically erasable programmable read-only memory (EEPROM). On old cards, you might be able
to completely replace the chip with a new one—again, if supplied by the manufacturer and if the
manufacturer did not hard-solder the BIOS to the printed circuit board. Most video cards use a
surface-mounted BIOS chip rather than a socketed chip. A BIOS you can upgrade using software is
referred to as a
flash
BIOS, and most video cards that offer BIOS upgrades use this method. Some
graphics cards, such as certain models based on the AMD Radeon HD 6900 and 7970 GPUs, include
two BIOS chips: one that is not upgradeable, and a second one that can be upgraded by the user for
higher overclocked performance.
Note
Video BIOS upgrades are sometimes referred to as
firmware upgrades
.
The Video Processor
The video processor (also known as the video chipset, video graphics processor, or GPU) is the
heart of any video adapter and essentially defines the card's functions and performance levels. Two
video adapters built using the same chipset will have the same basic capabilities. However, cards
built using the same chipset can vary in the clock speeds at which they run the chipset, memory, output
ports, and other components, as well as in the amount and type of memory installed. Therefore,
performance can vary. The software drivers that OSs and applications use to address the video
adapter hardware are written primarily with the chipset in mind. You can normally use a driver
intended for an adapter with a particular chipset on any other adapter using the same chipset, or the
same chipset families.
Identifying the Video and System Chipsets
Before you purchase a system or a video card, you should find out which chipset the video card or
