Table 1-5 Motherboard Form Factors

Form Factor	Dimensions (mm)	Details and Descriptions
ATX	305x244	The basic motherboard.
Micro ATX	244x244	A smaller square version ATX motherboard with
		fewer expansion slots.
ITX	215x191	Designed to be used with completely integrated
		devices. Not widely used, but inspired smaller
		mini-ITX design.

		Chapter 1: Hardware 17
Form Factor	Dimensions (mm)	Details and Descriptions
Mini-ITX	170x170	Designed to be used with completely integrated
		devices. Popular choice for Home Theater PCs and
		servers. Some feature a single PCIe x16 expansion
		slot.
BTX	325x266	Used by some retail and a few custom-built sys-
		tems; features integrated thermal module for cool-
		ing processor and memory modules.
NLX	254x228	Integrated AGP, NIC, and USB support. Now obso-
		lete.
LPX	330x229	Expansion cards are mounted on riser cards that
		can run parallel to motherboard or at a right angle
		and can, therefore, fit in to a smaller case. Now
		obsolete.

 

 

Expansion Cards and Slots

 

Expansion cards (also known as adapter cards) allow the motherboard to connect and control countless devices. Expansion cards connect to the motherboard via expansion slots. Adapter cards can also share some of the processing responsibility, which lightens the load on the CPU. Table 1-6 describes the standard expansion slots.

 

Table 1-6 Expansion Slots

Adapter Card / Bus Name Details and Descriptions

 

Bus Width

 

PCIe	x1
	x4
	x8
	x16

 

Supports full duplex (sends/receives data simultaneous-ly). Throughput is 250MBps per lane (PCIe version 1) or 500MBps per lane (PCIe version 2). Each lane is x1. Four lanes = x4. Eight lanes = x8. Sixteen lanes = x16.

 

Mini-PCIe	x1	1.5V, 3.3V version of PCIe x1 for laptops and note-
		books; mainly used for Wi-Fi
PCI		Current standard, 32 bit and 64 bit, shorter than ISA;
		usually white; 64-bit version has three inline connectors
		Two inline connectors; usually white

18 CompTIA A+ Quick Reference

 

Table 1-6 Continued

Adapter Card /	Bus Name	Details and Descriptions
Bus Width
Mini-PCI		33MHz, 3.3V, used in notebook and laptop computers
		for Wi-Fi and communications
PCI-X	64-bit	Same slot design as 64-bit PCI
		133MHz (version 1.0), 266 and 533MHz (version 2.0)
AGP version 1.0		Dedicated graphics card slot, inset from rear of mother-
(AGP 1x, 2x)		board; runs at 66MHz
		1x throughput 266MBps
		2x throughput 533MBps
		3.3V slot
AGP version 2.0		1066MBps throughput
(AGP 4x)		1.5V slot
AGP version 3.0		2133MBps throughput
(AGP 8x)		0.8V and 1.5V slot (cards backward compatible with
		AGP v2.0)
AGP Pro		Provides additional power; speeds vary
EISA		Old technology, 32-bit version of ISA; backward com-
		patible with ISA
ISA		Black
		Common in older PCs

 

 

Figure 1-8 shows the relative size and form factors of the common expansion slots. You should be able to identify these during your CompTIA A+ Certification exams.

Chapter 1: Hardware 19

 

 

AGP Pro

 

 

AGP 4x/8x

 

PCI 33MHz/32-bit

 

 

AGP 1x/2x

 

 

1. PCI Express x16 slot

2. PCI Express x1 slot

 

3. PCI Express x4 slot

 

4. PCI slot (32-bit, 33MHz)

 

 

Figure 1-8 Expansion slot comparison.