Specifications

117
Motherboard Types and Features
3
The last AGP standard, AGP 3.0, runs at 8x or 4x speeds. APG 3.0 cards can be installed in
an AGP 1.5-V slot, but signals are put on the data bus using 0.8 V. It’s best to install an AGP 3.0
card in a slot that is designed to support AGP 3.0 cards. However, if you install an AGP 3.0 card
in an older AGP 1.5-V slot, the card might or might not work, but the card will not be damaged.
An AGP video card will be keyed to 1.5 V or 3.3 V or a universal AGP video card has
both keys so that it can fit into either a 1.5-V keyed slot or a 3.3-V keyed slot. A universal
AGP video card also fits into a universal AGP slot. If an AGP video card does not make use
of the extra pins provided by the AGP Pro slot, it can still be inserted into the AGP Pro
slot if it has a registration tab that fits into the end of the Pro slot near the center of the
motherboard. In Chapter 7, you’ll learn about AGP video cards.
Notes
If you’re trying to buy an AGP video card to match a motherboard slot, you have to be really
careful. When reading an AGP ad, it’s hard to distinguish between AGP 3.3 V and AGP 3.0, but there’s a
big difference in these standards, and they are not interchangeable.
AMR AND CNR SLOTS
To reduce the total cost of a computer system, some older motherboards might have a small
expansion slot, about the length of a PCI Express x1 slot. This small slot can be an
audio/modem riser (AMR) slot or a communication and networking riser (CNR) slot
(see Figure 3-20). These small slots accommodate small, inexpensive expansion cards called
riser cards, such as a modem riser card, audio riser card, or network riser card. (These are
not the same riser cards used in NLX systems or riser cards used to extend an expansion
slot.) Part of a riser card’s audio, modem, or networking logic is on the card, and part is on
a controller on the motherboard. If you see an older motherboard and it has a short slot
beside a PCI or AGP slot, suspect that it’s a CNR or AMR slot. AMR and CNR slots are
rarely used today and it’s next to impossible to find the cards that fit them.
A+ 220-701
A+
220-701
1.2
CNR slot
Figure 3-20 A CNR slot is smaller than a PCI slot but about the same height
Image copyright 2009, Slobodan Djajic. Used under license from Shutterstock.com
A+ Exam Tip
The A+ 220-701 Essentials exam expects you to be familiar with an AMR slot, CNR
slot, and riser card, sometimes called a daughter board.
1435487389_ch03_CTP.qxd 7/30/09 5:22 PM Page 117