May 04, 2010
BIOS chip: We discuss BIOS chips in greater detail later in this chapter.
Chipset: Every motherboard has a number of integrated circuits (chips or ICs) permanently installed on different parts of the board. Each chip has a separate function. It is most common for these chips to all be from a single manufacturer. You might see ASUS? brand motherboards, for example, with chipsets from Intel? or Via. Some companies such as Intel make their own motherboards in addition to chipsets for competitors’ products. Manufacturers such as these virtually always use their own chipsets in their motherboards.
AGP slot: All motherboards made in the last several years that don’t have built-in video, and some that do, have an accelerated graphics port (AGP) slot. This is the slot for a video adapter. Figure 3.3 shows an AGP slot. See Chapter 8, “Video, Sound, Modems, and Network Adapters,” for more information on video adapters.
Figure 3.3: AGP video slot.
DVO connector: Some motherboards have header connectors for digital video adapters. The connectors are called DVO and the adapters are called DVI. Figure 3.4 shows a DVO connector.
Figure 3.4: DVO video header connector.
By : Book-PC Repair and Maintenance: A Practical Guide
March 01, 2010
Loose adapters in AGP slots are often the culprits for video problems. Retention clips that retrofit to most AGP slots were introduced to hold them in place. Figure 8.3 shows an AGP retention clip in place. If a PC with this type of AGP slot loses its video for no apparent reason, try a retention clip. The video adapter you use must have a notched tab to work with the retention clip.
Figure 8.3: AGP retention clip.
Dot Pitch
Dot pitch is a measurement of how close the picture elements are to one another. The closer they are, the higher the resolution can be, so the lower the number, the better. Cheap monitors have larger dot pitches and are harder on users’ eyes. Select .028 mm or lower.
Testing Displays
There are a few ways to test monitors. DisplayMate? (displaymate.com) offers testing utilities and hardware for any type of video display. They have products for end users, technical users, and advanced users. If you plan to test monitors, their products are definitely appropriate.
General computer testing utilities, such as products from PC Certify and Micro-2000, and even some products that are released by computer makers also include video tests. See Chapter 11 for more on general diagnostic products.
Monitor Installation
In the vast majority of cases, monitors need only to be plugged into the video adapter outputs, be they SVGA or DVI. Some monitors are recognized and installed automatically by Windows. In some situations, Windows will need a driver in order for the monitor to display more than base video. This is most likely to happen with an older version of Windows, or a monitor that uses new technology.
By : Book-PC Repair and Maintenance: A Practical Guide
February 21, 2010
Video adapters are available in AGP, PCI, and other older interfaces.
Accelerated Graphics Port (AGP)
AGP represents an advancement over previous video interfaces. It allows for more efficient transfer of data between the chipset and the graphics controller. There have been three different connectors used for AGP. These are designed so that only the correct card can be inserted into a given slot. Each connector represents a different standard that includes a different signal voltage and other parameters.
PCI Video Cards
PCI video cards are rarely used for primary video adapters anymore; they are almost always used when built-in video fails or to feed video to second monitors. In the late 1990s, however, there were systems in which the video did come in PCI.
DVI Video
DVI video is becoming more popular, especially as digital flat-panel monitors become more commonplace. DVI video is available mainly in AGP video cards and as built-in video. DVI video can be better and faster than analog video. A computer’s VGA port outputs analog video that the video adapter has converted from digital using a Random Access Memory Digital-to-Analog Converter (RAMDAC) chip. All flat-panel monitors are digital, but those with VGA connectors have to convert the analog signal back to digital. Video that has been converted from digital to analog and back to digital again loses some quality. Therefore, it is best to use a digital flat panel monitor with a DVI output. Early digital flat panel monitors used oddball video connectors: the MDR-20 and the Plug & Display connector. The DVI connectors shown aren’t compatible with these, but a few adapters are available. Search the Internet to find them.
For more information on DVI, or go to matrox.com/mga/ products/tech_info/dvi_backgrounder.cfm.
Older Video Interfaces
The only other interfaces you could run into on PCs built since the mid-1990s are ISA, which fit into ISA slots, and VESA Local (VL) Bus. VL Bus adapters fit only into VL Bus motherboard slots. These rather long slots are found only on PCs from the mid-1990s.
Speed
Video speed comes from the type of AGP port, the chipset, the RAMDAC chip, and the type and amount of video memory. With applications that are used to manipulate images, greater speed and memory amount allows for much faster loading and manipulation of images. Moreover, the faster the RAMDAC chip, the faster the refresh rate. We discuss refresh rates later in this chapter.
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