CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [331]
If you use your computer only for 2-D programs (most office applications such as word processors, e-mail, and Web browsers are 2-D), most of the features of the more advanced graphics cards will do you little good. If you’re not a gamer, you can meet your needs with a cheap, low-end video card.
Video Memory
Video memory is crucial to the operation of a PC. It is probably the hardest-working set of electronics on the PC. Video RAM constantly updates to reflect every change that takes place on the screen. When you’re working with heavy-duty applications (such as games), video memory can prove to be a serious bottleneck in three ways: data throughput speed, access speed, and simple capacity.
Manufacturers have overcome these bottlenecks by upping the width of the bus between the video RAM and video processor; using specialized, super-fast RAM; and adding more and more total RAM.
First, manufacturers reorganized the video display memory on cards from the typical 32-bit-wide structure to 64, 128, or even 256 bits wide. Because the system bus is limited to 32 or 64 bits, this would not be of much benefit if video display cards weren’t really coprocessor boards. Most of the graphics rendering and processing is handled on the card by the video processor chip rather than by the CPU. The main system simply provides the input data to the processor on the video card. Because the memory bus on the video card is as much as eight times wider than the standard 32-bit pathway (256 bits), data can be manipulated and then sent to the monitor much more quickly (Figure 19-44).
Figure 19-44 Wide path between video processor and video RAM
Specialized types of video RAM have been developed for graphics cards, and many offer substantial improvements in video speeds. The single most important feature that separates DRAM from video RAM is that video RAM can read and write data at the same time. Table 19-3 shows a list of common video memory technologies used yesterday and today—make sure you know these for the exams!
Table 19-3 Video RAM Technologies
Finally, many advanced 3-D video cards come with huge amounts of video RAM. It’s very common to see cards with 64, 128, 256, or 512 MB or even 1 GB of RAM! Why so much? Even with PCI Express, accessing data in system RAM always takes a lot longer than accessing data stored in local RAM on the video card. The huge amount of video RAM enables game developers to optimize their games and store more essential data on the local video RAM.
Connections
Modern video cards offer connections to one or more PC monitors. Many also sport connectors for non-monitors, such as televisions. The video card in Figure 19-45 has three connectors: VGA, DVI-I, and S-video. Other connectors enable the video card to connect to composite, component, and even high-definition devices.
Figure 19-45 Video card connectors, VGA, S-video, and DVI-I
For Standard Monitors
You know about the standard monitor connectors, VGA and DVI, from the monitor discussion earlier. About the only thing to add is that most DVI connections on video cards these days natively support analog signals. You can use a simple DVI-to-VGA adapter, for example, for connecting a VGA cable to a video card.
Apple Macintosh desktop models use a DisplayPort connection rather than VGA or DVI for connecting to a monitor. Dell offers support for DisplayPort as well at the time of this writing. Figure 19-46 shows a DisplayPort jack on a Dell portable.
Figure 19-46 DisplayPort jack
For Multimedia Devices
Video cards can have one or more standard connections plus non-standard connections for hooking the PC to a multimedia device, such as a television, DVD player, or video camera. The earliest type of connector commonly found is the S-video connector. This provides decent-quality video output or, in some cases, input. More commonly now you see both a proprietary round connector that supports S-video