Hardware Reference
In-Depth Information
See Accelerated Graphics Port , p. 237 ( Chapter 4 ) .
Caution
Be sure to check AGP compatibility before you insert an older (AGP 1x/2x) card into a
system designed for AGP 4x or 8x. Even if you can physically insert the card, a mismatch
between the card's required voltage and the AGP slot's voltage output can damage the
motherboard. Check the motherboard manual for the card types and voltage levels the AGP
slot supports.
SomeAGPcardscanuseeither3.3Vor1.5Vvoltagelevels,adjustedviaanonboardjumper.
These cards typically use an AGP connector that is notched for use with either AGP 2x or
AGP4xslots,aspicturedin Chapter4 , MotherboardsandBuses . ”Besuretosetthesecards
to use 1.5V before using them in motherboards that support only 1.5V signaling.
PCIe
PCIe began to show up in systems in mid-2004 and has filtered down to all systems that
use discrete video cards or have integrated video that can be upgraded. Despite the name,
PCIe uses a high-speed bidirectional serial data transfer method, and PCIe channels (also
known as lanes ) can be combined to create wider and faster expansion slots. (Each lane
provides 250MBps, 500MBps, or 1,000MBps data rate in each direction.) Because PCIe
is technically not a bus, unlike PCI, the slots do not compete with each other for band-
width. PCIe graphics cards use up to 16 lanes (x16) to enable speeds of 4GBps, 8GBps,
or 16GBps in each direction, as seen in Table 12.8 .
Table 12.8 PCIe Video Card Bandwidth
Most PCIe implementations include one x16 slot for video and two or more x1 slots for
other add-on cards, as well as legacy PCI slots. Systems that support NVIDIA's SLI or
AMD CrossFire X dual PCIe video card technologies have up to three or four PCIe video
slots running at x8 or x16 speed.
The Display Interface
The display interface connects the video display adapter to the monitor or display. Over
the years, several methods of connecting monitors have been available. Some of these in-
terfaces have been analog, and others have been digital. The first interfaces used in the
 
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