Motherboard Flashcards
Motherboard
Introduction
The motherboard provides the foundation for the personal computer. Every piece of hardware, from the CPU to the lowliest expansion card, directly or indirectly plugs into the motherboard. The motherboard contains the wires—called traces—that make up the buses of the system. It holds the vast majority of the ports used by the peripherals, and it distributes the power from the power supply. Three variable and interrelated characteristics define modern motherboards: form factor, chipset, and components.
Form Factor
determines the physical size of the motherboard as well as the general location of components and ports.
Chipset
defines the type of processor and RAM the motherboard requires. It also determines to a degree the built-in devices the motherboard supports, including the expansion slots.
Component
the built-in components determine the core functionality of the system.
Exam Tip
Exam Tip: CompTIA A+ 1001 exam objective 3.5 focuses specifically on motherboards you find in classic Windows and Linux-based desktop PCs. This style of motherboard enables techs to do such things as update components. Thus, this chapter uses the term PC pretty much throughout.
Note, though, that every personal computing device has a main circuit board to which CPU, RAM, storage, and more connect. Some device makers call this PCB a motherboard. Others, like Apple, call it a logic board. Regardless of the label, the primary function is the same—it’s the foundational component of the computer.
Form Factors
Form factors are industry-standardized shapes and layouts that enable motherboards to work with cases and power supplies. A single form factor applies to all three components. All motherboards come in a basic rectangular or square shape, but vary in overall size and in the layout of built-in components. You need to install a motherboard in a case designed to fit it, so the ports and slot openings on the back fit correctly.
ATX Form Factor
The full-sized ATX form factor is 12 by 9.6 inches. The microATX motherboard floats in at a svelte 9.6 by 9.6 inches (usually), or about 30% smaller than standard ATX. It uses the standard ATX connections. A microATX motherboard fits into a standard ATX case or in the much smaller microATX cases. Note that not all microATX motherboards have the same physical size. FlexATX motherboards, which have all but disappeared these days, had maximum dimensions of just 9 by 7.5 inches, which makes them the smallest motherboards in the ATX standard.
ITX
Not everyone wants or needs a huge desktop system. Around 2001, chipset maker VIA Technologies created a small form factor (SFF) motherboard, the ITX. The ITX itself wasn’t a success, but VIA created a number of even smaller form factors that today populate the SFF market: Mini-ITX, Nano-ITX, and Pico-ITX.
Mini-ITX is the largest and the most popular of the three ITX form factors. At a miniscule 6.7 by 6.7 inches, Mini-ITX dominates the SFF space.
If you think that’s small, Nano-ITX at 4.7 by 4.7 inches and Pico-ITX at 3.8 by 2.8 inches are even smaller. These tiny motherboard form factors are commonly used for embedded systems and highly specialized devices such as routers.
One of the great benefits of these SFF motherboards is the tiny amount of power needed to support them. ITX power supplies are quite small compared to a typical power supply. Lower power usage produces less heat, thus enabling passive cooling on many SFF systems. The lack of fan noise makes them ideal for media center PCs.
Chipset
Every PC motherboard has a chipset, one or more discrete integrated circuit chips that support the CPU’s interfacing to some of the other devices on the motherboard. The chipset determines the type of processor the motherboard can accept, the type and capacity of RAM, and the sort of internal and external devices that the motherboard supports.
Motherboard Drivers
The system ROM chip provides part of the BIOS for the chipset, but only at a barebones, generic level. The chipset still needs support for the rest of the things it can do. So how do expansion devices get BIOS? From software drivers, of course, and the same holds true for modern chipsets.
You have to load the proper drivers for the specific OS to support all of the features of today’s chipsets. Without software drivers, you’ll never create a stable, fully functional PC. Most motherboards ship with an optical disc with drivers, support programs, and extra-special goodies such as antivirus software.
Choosing the Motherboard and Case
First, determine what motherboard you need. What CPU are you using? Will the motherboard work with that CPU? Because most of us buy the CPU and the motherboard at the same time, make the seller guarantee that the CPU will work with the motherboard. How much RAM do you intend to install? Are extra RAM sockets available for future upgrades?
A number of excellent motherboard manufacturers currently exist. Some of the more popular brands are ASUS, BIOSTAR, GIGABYTE, Intel, and MSI. Your supplier may also have some lesser-known but perfectly acceptable brands of motherboards. As long as the supplier has an easy return policy, it’s fine to try one of these.
Second, make sure you’re getting a form factor that works with your case. Don’t try to put a regular ATX motherboard into a microATX case!
Third, all motherboards come with a technical manual, better known as the motherboard book. You must have this book! This book is your primary source for all of the critical information about the motherboard. If you set up CPU or RAM timings incorrectly in CMOS, for example, and you have a dead PC, where would you find the CMOS-clear jumper? Where do you plug in the speaker? Even if you let someone else install the motherboard, insist on the motherboard book; you will need it.
Fourth, pick your case carefully. Cases come in many sizes: slimline, desktop, minitower, midtower, tower, and cube. Plus, you can get specialized cases, such as tiny cases for entertainment systems or ones that fit the same format as a stereo receiver or DVD player. The latter case is called a home theater PC (HTPC). HTPCs aren’t as popular as they once were because digital video recorders (DVRs) are provided by most cable and satellite TV providers these days, but they still have their fans.
Slimline and desktop models generally sit on the desk, beneath the monitor. The various tower cases usually occupy a bit of floor space next to the desk. The minitower and midtower cases are the most popular choices. Make sure you get a case that fits your motherboard—most microATX cases are too small for a regular ATX motherboard. Cube cases generally require a specific motherboard, so be prepared to buy both pieces at once. A quick test-fit before you buy saves a lot of return trips to the supplier.
Standoffs
Unscrew the motherboard. It will not simply lift out. The motherboard mounts to the case via small connectors called standoffs that slide into keyed slots or screw into the bottom of the case. Screws then go into the standoffs to hold the motherboard in place. Be sure to place the standoffs properly before installing the new motherboard.
Attaching wires
The next part of motherboard installation is connecting the LEDs, buttons, and front-mounted ports on the front of the box. This is sometimes easier to do before you install the motherboard fully in the case. You can trace the wire leads from the front of the case to the appropriate connector pins on the motherboard. These usually include the following:
Soft power button Reset button Speaker Hard drive activity light Power light USB FireWire Sound Thunderbolt
Note
Note: In Lesson 6, we’ll go into power supplies and their connectors, so I’ll save the details until then. Of fundamental importance here is that modern motherboards require two connectors from the power supply. The main power connector is called P1; the secondary connector is usually referred to as P4.
POST card
A POST card can be helpful with the system test because you won’t have to add the speaker, a video card, monitor, and keyboard to verify that the system is booting. If you have a POST card, start the system, and watch to see if the POST takes place—you should see a number of POST codes before the POST stops.
If you don’t have a POST card, install a keyboard, speaker, video card, and monitor. Boot the system, and see if the BIOS information, a logo for the manufacturer, or some other text shows up on the screen. If it does, you’re probably okay. If it doesn’t, it’s time to refer to the motherboard book to see where you made a mistake.
expansion slots
Expansion slots have been part of the PC from the very beginning. Way back then, IBM created the PC with an eye to the future; the original IBM PC had slots built into the motherboard—called expansion slots
expansion bus
The slots and accompanying wires and support chips on the first PC and on the latest and greatest PC are called the expansion bus
Chipset
As you’ve learned, every device in the computer—whether soldered to the motherboard or snapped into a socket—connects to the external data bus and the address bus. The expansion slots are no exception. They connect to the rest of the PC through the chipset.
PCI (Peripheral Component Interconnect)
Intel introduced the Peripheral Component Interconnect (PCI) bus architecture in the early 1990s, and the PC expansion bus was never again the same. Intel made many smart moves with PCI, not the least of which was releasing PCI to the public domain to make it very attractive to manufacturers. PCI provided a wider, faster, more flexible alternative than any previous expansion bus. The exceptional technology of the new bus, combined with the lack of a price tag, made manufacturers quickly drop older buses and adopt PCI.
Equally impressive was that PCI devices were (and still are) self-configuring, a feature that led to the industry standard that became known as plug and play (PnP).
Mini-PCI
Mini-PCI
PCI made it into laptops in the specialty Mini-PCI format. Mini-PCI was designed to use low power and to lie flat—both good features for a laptop expansion slot.
PCI Express
PCI Express (PCIe) is the latest and fastest, expansion bus in use today. As its name implies, PCI Express is still PCI, but it uses a point-to-point serial connection instead of PCI’s shared parallel communication. A PCIe connection uses one wire for sending and one for receiving. Each of these pairs of wires between a PCIe controller and a device is called a lane.
Each version of PCIe increases the lane speed. PCIe 1.x, for example, runs each lane at 2.5 gigatransfers per second (GTps). PCIe 2.x (introduced in 2007) doubles the lane speed to 5 GTps. PCIe 3.x ups it to 8 GTps. The transfer rate describes the number of operations happening per second. With serial communication, you almost get a one-to-one correlation between transfer rate and binary data rate. The most common PCIe slot is the 16-lane (×16) version most commonly used for video cards. There is also a small form factor version of PCI Express for mobile computers called PCI Express Mini Card, or Mini-PCIe.
PCI Express Mini Card, or Mini-PCIe
There is also a small form factor version of PCI Express for mobile computers called PCI Express Mini Card, or Mini-PCIe.
PCI express bandwidth
The bandwidth generated by a ×16 slot is far more than anything other than a video card would need, so most PCIe motherboards also contain PCIe slots with fewer lanes. Currently ×1 is the most common general-purpose PCIe slot. It provides more than enough bandwidth for devices such as consumer-level network interface cards and sound cards.
Installing process PCI
Exam Tip: The four steps involved in installing expansion cards apply to all types of expansion cards. The CompTIA A+ exams will ask you about cards ranging from common—sound, video, and networking—to other specific cards for USB, Thunderbolt, and eSATA, wireless and cellular networking and more, all of which we’ll cover in their proper chapters in this course. You install any of them using the same four steps: knowledge, physical installation, device drivers, and verification.
