Introduction to motherboards

The primary component of a computer is the motherboard (sometimes called the "mainboard"). The motherboard is the hub which is used to connect all of the computer's essential components.

As its name suggests, the motherboard acts as a "parent" board, which takes the form of a large printed circuit with connectors for expansion cards, memory modules, the processor, etc.

The input-output connectors

The motherboard has a certain number of input/output sockets found on the rear panel.

Most motherboards have the following connectors:

• A serial port, for connecting old peripherals;
• A parallel port, mainly for connecting old printers;
• USB ports (1.1, low-speed, or 2.0, high-speed), for connecting more recent peripherals;
• RJ45 connector (called LAN or ethernet port) used for connecting the computer to a network. It corresponds to a network card integrated into the motherboard;
• VGA connector (called SUB-D15), for connecting a monitor. This connector interfaces with the built-in graphics card;
• Audio plugs (Line-In, Line-Out and microphone), for connecting sound speakers or a hi-fi system, as well as a microphone. This connector interfaces with the built-in sound card;

Expansion slots

Expansion slots are compartments into which expansion cards can be inserted. These are cards which give the computer new features or increased performance. There are several types of slots:

• ISA slots (Industry Standard Architecture): For inserting ISA slots. The slowest ones are 16-bit.
• VLB slots (Vesa Local Bus): Bus formerly used for installing graphics cards.
• PCI slot (Peripheral Component InterConnect): used for connecting PCI cards, which are much faster than ISA cards and run on 32 bits
• AGP slot (Accelerated Graphic Port): A fast port for a graphics card.
• PCI Express slot (Peripheral Component InterConnect Express): Faster bus architecture than AGP and PCI buses.
• AMR slot (Audio Modem Riser): This type of slot is used for connecting mini-cards to PCs which are built for it.

The processor socket

The processor (also called the microprocessor) is the computer's brain. It runs programs using a set of instructions. The processor is characterised by its frequency, the rate at which it executes instructions. This means that an 800 MHz processor can carry out 800 million operations per second.

The motherboard has a slot (sometimes several, for multi-processor motherboards) into which the processor is inserted, called the processor socket or slot.

• Slot: A rectangular connector into which the processor is mounted vertically.
• Socket: In addition to being the general term, it also refers more specifically to a square-shaped connector with many small connectors into which the processor is directly inserted.

Within these two large families, there are different versions used, depending on the type of processor. Whatever slot or socket is used, it is essential that the processor be inserted gently, so that none of its pins are bent (it has hundreds of them). To make inserting them easier, a concept called ZIF (Zero Insertion Force) has been created. ZIF sockets have a small lever, which, when lifted, allows the processor to be inserted without applying any pressure, and when lowered, it holds the processor in place.

The processor generally includes some sort of foolproof device, in the form of a notched corner or coloured markings, which must be aligned with the corresponding markings on the socket.

Since the processor releases heat, it is necessary to dissipate it, to keep the circuits from melting. This is why it is generally mounted atop a heat sink (sometimes called a cooler or radiator), which is made of a metal which conducts heat well (copper or aluminium) in order to increase the microprocessor's heat transfer surface. The heat sink includes a base in contact with the processor and fins in order to increase the heat transfer surface. A fan generally accompanies the cooler in order to improve air circulation around it and to improve the heat transfer. The unit also includes a fan which vents hot air from the case and let fresh air come in from outside.

The CMOS clock and battery

The real time clock (or RTC for short) is a circuit which synchronises system signals. It is made from a crystal which, as it vibrates, gives off pulses (called timer ticks) in order to keep the system elements running on the same time. The timer frequency (expressed in MHz) the number of times the crystal vibrates each second, i.e. the number of timer ticks per second. The higher the frequency, the more information the system can process.

When the computer is turned off, the power supply stops providing electricity to the motherboard. When the computer is turned on again, the system is still on the right time. An electronic circuit, called the CMOS (Complementary Metal-Oxyde Semiconductor, sometimes called the BIOS CMOS), saves some system information, such as the time, the system date, and a few essential system settings.

The CMOS is kept powered by a battery (a button battery), or a battery located on the motherboard. Information on the hardware installed in the computer (such as the number of tracks or sectors on each hard drive) are stored in the CMOS. As the CMOS is a form of slow storage, certain systems sometimes recopy the CMOS's content into the RAM (fast storage); the term "memory shadow" is used to describe this process of copying the data into RAM.

The "complementary metal-oxide semiconductor" is a transistor manufacturing technology, the latest in a long line which includes the TTL ("Transistor-transistor-logic"), the TTLS (TTL Schottky) (faster), or the NMOS (negative channel) and PMOS (positive channel).

The CMOS allows many complementary channels to run on a single chip. Compared with TTL or TTLS, CMOS is much slower, but it consumes far less energy, which is why it is used in computer clocks, which run on batteries. The term CMOS is sometimes incorrectly used to refer to computer clocks.

When the system time keeps getting reset, or the clock runs late, all that is usually necessary is to change the battery.

Integrated components

The motherboard includes some on-board components, meaning that they are integrated into its printed circuitry:

• The chipset, a circuit which controls the majority of resources (including the bus interface with the processor, cache memory and random-access memory, expansion cards, etc.)
• The CMOS clock and battery,
• The BIOS,
• The system bus and the expansion bus.

What's more, recent motherboards generally include a number of onboard multimedia and networking devices which can be disabled:

• integrated network card;
• integrated graphics card;
• integrated sound card;
• upgraded hard drive controllers.

Integrated components

The motherboard includes some on-board components, meaning that they are integrated into its printed circuitry:

• The chipset, a circuit which controls the majority of resources (including the bus interface with the processor, cache memory and random-access memory, expansion cards, etc.)
• The CMOS clock and battery,
• The BIOS,
• The system bus and the expansion bus.

What's more, recent motherboards generally include a number of onboard multimedia and networking devices which can be disabled:

• integrated network card;
• integrated graphics card;
• integrated sound card;
• upgraded hard drive controllers.

Motherboard form factor

The term "form factor" is normally used to refer to the motherboard's geometry, dimensions, arrangement, and electrical requirements. In order to build motherboards which can be used in different brands of cases, a few standards have been developed:

• AT baby/AT full format is a format used in the earliest 386 and 486 PCs. This format was replaced by the ATX format, which shape allowed for better air circulation and made it easier to access the components;
• ATX: The ATX format is an upgrade to Baby-AT. It was intended to improve ease of use. The connection device on an ATX motherboard is designed to make plugging in peripherals as easy as possible (for example, the IDE connectors are located beside the disks.) What's more, motherboard components are arranged in parallel, so as to improve heat removal.
  • ATX standard: The ATX standard format is traditionally 305x244 mm. It includes an AGP connector and 6 PCI connectors.
  • micro-ATX: The microATX format is an upgrade to ATX, which has the same primary advantages in a smaller format (244x244 mm), with a lower cost. Micro-ATX includes an AGP connector and 3 PCI connectors.
  • Flex-ATX: FlexATX is an expansion of microATX which offers manufacturers greater flexibility when designing their computers. It includes an AGP connector and 2 PCI connectors.
  • mini-ATX: miniATX is a compact alternative to the format microATX (284x208 mm), and includes an AGP connector and 4 PCI connectors instead of 3 that come with microATX. It is mainly intended for mini-PCs (barebone computers).
• BTX: The BTX format (Balanced Technology eXtended), supported by Intel, is a format designed to improve upon the arrangement of components, so as to optimise air circulation, acoustics, and heat dissipation. The various connectors (memory slots, expansion slots) are aligned in parallel, in the direction in which air circulates. Additionally, the microprocessor is located in the front end of the case, by the air intake, where the air is freshest. The BTX power cord is the same as with ATX power supplies. The BTX standard defines three formats:
  • BTX standard, with standard dimensions of 325x267 mm;
  • micro-BTX, with small dimensions (264x267 mm);
  • pico-BTX, with much smaller dimensions (203x267 mm).
• ITX: The ITX format (Information Technology eXtended), supported by Via, is an extremely compact format designed for miniature configurations such as mini-PC. There are two major ITX formats:
  • mini-ITX, with small dimensions (170x170 mm) and a PCI slot;
  • nano-ITX, with extremely small dimensions (120x120 mm) and a miniPCI slot. For this reason, the choice of the motherboard (and its form factor) depends on which case is chosen. The table below summarises the characteristics of the various form factors.

motherboard nowdays

The main circuit board of a microcomputer. The motherboard contains the connectors for attaching additional boards. Typically, the motherboard contains the CPU, BIOS, memory, mass storage interfaces, serial and parallel ports, expansion slots, and all the controllers required to control standard peripheral devices, such as the display screen, keyboard, and disk drive. Collectively, all these chips that reside on the motherboard are known as the motherboard's chipset.

On most PCs, it is possible to add memory chips directly to the motherboard. You may also be able to upgrade to a faster PC by replacing the CPU chip. To add additional core features, you may need to replace the motherboard entirely.

Description

• The best way to describe the motherboard goes along well with my human body analogy that I used for the CPU. The CPU is the brain, and the motherboard is the nervous system. Therefore, just as a person would want to have fast communication to the body parts, you want fast communication between the parts of your computer. Fast communication isn't as important as reliable communication though. If your brain wanted to move your arm, you want to be sure the nervous system can accurately and consistently carry the signals to do that! Thus, in my opinion, the motherboard is the second most important part of the computer.
• The motherboard is the circuit board to which all the other components of the computer connect in some way. The video card, sound card, IDE hard drive, etc. all plug into the motherboard's various slots and connectors. The CPU also plugs into the motherboard via a Socket or a Slot.

GIGABYTE First With USB 3.0 Motherboard Certification

Taipei, Taiwan, January 4, 2010 - GIGABYTE TECHNOLOGY Co., Ltd, a leading manufacturer of motherboards, graphics cards and other computing hardware solutions today proudly announced that the GA-P55A-UD3 motherboard is the world’s first motherboard to pass USB-IF (Universal Serial Bus-Implementers Forum) certification. As the first motherboard to receive such certification, the GIGABYTE GA-P55A-UD3 is qualified to display the SuperSpeed USB logo, assuring customers their motherboard provides all the speed and power efficiency enhancements that SuperSpeed USB offers, including up to 10x data transfer speed boost over USB 2.0 as well as compatibility with existing USB 2.0 products.

In order to receive certification, the GIGABYTE GA-P55A-UD3 underwent strict compliance and product quality testing from the USB-IF. Other GIGABYTE motherboard models with onboard USB 3.0 are currently being tested and are expected to pass certification within the next couple of weeks.

Motherboard & Memory Sockets Details

Most motherboards today come with between 2 and 8 sockets for the insertion of memory. These are usually either SIMMs (Single Inline Memory Modules) or DIMMs (Dual Inline Memory Modules). These sockets .can be of different sizes. The motherboard usually labels these sockets "SIMMO" th'rough"SIMM7" or "DIMMl" through "DIMM3", etc. The sockets are almost always filled starting with the lowest numbered socket first. Most Pentium class or higher motherboards require SIMMs to be inserted in pairs, but DIMMs may be inserted individually.