Motherboard, Processor and Memory form the main components of a computer system. 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. Motherboard is the main circuit board of a computer. It contains connectors and ports for attaching additional boards and peripheral devices. It has multiple controller chips on the motherboard to control standard devices such as keyboard, disk drive, etc. All the controller chips together are called as chipset. The Motherboard is the main circuit board of a computer. The motherboard contains the connectors for attaching additional components. The collection of chips and controllers is known as the 'chipset'. The motherboard is a collection of devices that control the flow of data and operating electricity for all the primary components in a PC. The Motherboard has two main processing chips on it called the Northbridge and the Southbridge. The Northbridge handles all the data flows to and from the main memory and also all the CPU transactions. The Southbridge handles the data for most of the ports. CLASSIFICATION-: # Integrated and nonintegrated are the two major types of Motherboards based on the way components were installed or designed on it. . 1.Integrated system boards have most of the components included into the motherboard circuitry that would otherwise be installed as expansion cards, thus the name integrated. Integrated system boards were designed for their simplicity. A major drawback is that even in case one component breaks down then the entire motherboard needs to be replaced. Though they are cheaper to produce, they are more expensive to repair. ATX mother boards are common integrated motherboards. 2. Nonintegrated motherboards have lot of expansion cards. The major components are the video card, disk controllers. Nonintegrated motherboards can be easily identified because each expansion slot is usually occupied by one of the components. Nonintegrated system boards are further classified based on their form factors (design): mainly into 2 types AT and ATX. The AT motherboards are the first modern form factor to be widely used. AT stands for Advanced Technology & it was released by IBM in 1984. The PC and XT form factors that preceded it were quite uncommon. There are a few computers that still use AT and its variant Baby AT, but current standards are in favor of ATX. AT was not a huge technological advancement from older form factors. The biggest advancement was the 'tower' design and a power switch in the front. The AT power supply provided 192 watts, thrice more than older form factors. The AT motherboard is 12 inches (305 mm) and it won't fit in 'mini-tower cases' or 'mini desktop'. One of the major problems with the width of this board it takes up space behind the drive bays making installation of new drives difficult. The power connectors for AT motherboards are almost identical with 6-pin cords. The two connectors are not physically distinguishable, leading to damage of the motherboard when they were connected incorrectly. Baby AT is a variant of AT, introduced by IBM in 1985. Baby AT motherboards were popular as they were cheaper and smaller. These motherboards have the same functionality as AT motherboards but the width is reduced from 12' to 8.5' and are marginally longer. AT and Baby AT motherboards were the first PC motherboards to have built in sockets (headers) for I/O ports (serial, parallel, etc.). The serial and parallel port connectors are usually attached using cables that go between the physical connectors mounted on the back of the case and headers (pin connectors). These motherboards are distinguished by their shape, and by the presence keyboard connector soldered onto the motherboard. They were widely used in 386, 486 and early Pentium computers. The AT and Baby AT form factors have the processor socket(s)/slot(s) and memory sockets at the front of the motherboard. Long expansion cards and drives were designed to extend over them. Older processors and memory chips were small and put directly onto the motherboard. As processors became larger, the form factor did not have space to fit the combination of processor, heat sink, and fan. The introduction of SIMM/DIMM sockets, the concept of direct memory installation became obsolete. The ATX form factor was later on designed by Intel in order to overcome the above issues. ATX Motherboards that were introduced in 1995 quickly replaced older Baby AT & AT computers. ATX (Advanced Technology EXtended motherboard) improves on the previous Baby AT & AT form factors, by rotating the orientation of the board 90 degrees. This allowed for a more efficient design, with disk drive cable connectors nearer to the drive bays and the CPU closer to the power supply and cooling fan. ATX is not an abbreviation and is actually a trademark that belongs to Intel. The ATX uses a new specification of power supply that can be powered on or off by a signal from the motherboard. This allows notebook-style power management and software-controlled shutdown and power-up. A 3.3V output is also provided directly from the power supply. The ATX power supply has a side vent that blows air from the outside directly across the processor and memory modules, allowing passive heatsinks to be used in most cases, thereby reducing system noise. Mini-ATX is simply a smaller version of a full-sized ATX board. The AT standard had only a keyboard connector. Other common I/O connectors (serial & parallel ports etc) had to be mounted individually. The ATX was the first computer motherboard to not only include I/O support (serial, parallel, mouse, etc.), but to place all the connectors directly (soldered) onto the motherboard. ATX allowed each motherboard manufacturer to put these ports in a rectangular area on the back of the system, with an arrangement they could define themselves. Prior to the ATX, only the keyboard connector was attached to the motherboard. AT-style computer cases had a power button that was directly connected to the system power supply unit (PSU). The Power could be managed with proper BIOS support. Instead of two similar-looking power connectors (that could sometimes be misconnected causing short-circuits) ATX used one large 20-pin power connector, which made installation much easier and safer. The newer ATX specification defines a 24-pin power connector to support the power requirements of PCI Express. Maximum measures of ATX board are 12' x 9.6' (305mm x 244mm). A Full ATX is 12' wide x 9.6' deep & a Mini-ATX is 11.2' wide x 8.2' deep. Apart from above mentioned advantages ATX form factors also provides Improved Design for Upgradeability, Reduces Drive Bay Interference, Reduces Expansion Card Interference & has Better Air Flow. Some related designs include mini-ATX and microATX. MicroATX offers same benefits as ATX form factor but by reducing the physical size of the motherboard it improved the overall system design costs. This was done by reducing the number of I/O slots supported on the board. The microATX form factor provides more space at the rear to reduce emissions from using integrated I/O connectors. ATX will eventually be replaced by BTX. NLX is a new form factor used in 'low profile' motherboard types. They have a unique design where the expansion slots are placed sideways on a special riser card to optimally use the space. . Some manufactures design and manufacture their own motherboard designs, which don't conform to either standard. Basically, the components are laid out differently than an AT or ATX, but it will work as a PC. Such motherboard is known as a proprietary design motherboard. The BTX (Balanced Technology Extended) form factor will to be the replacement for the ATX form factor. It was proposed by Intel to address some of the issues that arose from using newer technologies, which demand more power and produce more heat on motherboards compliant with the ATX specification. How motherboard Works The motherboard's main job is to hold the computer's microprocessor chip and let everything else connect to it. Everything that runs the computer or enhances its performance is either part of the motherboard or plugs into it via a slot or port. A motherboard allows all the parts of your computer to receive power and communicate with one another. The shape and layout of a motherboard is called the form factor. The form factor affects where individual components go and the shape of the computer's case. There are several specific form factors that most PC motherboards use so that they can all fit in standard cases. The form factor is just one of the many standards that apply to motherboards. Some of the other standards include: The socket for the microprocessor determines what kind of Central Processing Unit (CPU) the motherboard uses. The chipset is part of the motherboard's logic system and is usually made of two parts - the northbridge and the southbridge. These two 'bridges' connect the CPU to other parts of the computer. The Basic Input/Output System (BIOS) chip controls the most basic functions of the computer and performs a self-test every time you turn it on. Some systems feature dual BIOS, which provides a backup in case one fails or in case of error during updating. The real time clock chip is a battery-operated chip that maintains basic settings and the system time. The slots and ports found on a motherboard include: Peripheral Component Interconnect (PCI)- connections for video, sound and video capture cards, as well as network cards Accelerated Graphics Port (AGP) - dedicated port for video cards. Integrated Drive Electronics (IDE) - interfaces for the hard drives Universal Serial Bus or Firewire - external peripherals Memory slots Some motherboards also incorporate newer technological advances: Redundant Array of Independent Discs (RAID) controllers allow the computer to recognize multiple drives as one drive. PCI Express is a newer protocol that acts more like a network than a bus. It can eliminate the need for other ports, including the AGP port. Rather than relying on plug-in cards, some motherboards have on-board sound, networking, video or other peripheral support. In the early days of PC computers, all processors had the same set of pins that would connect the CPU to the motherboard, called the Pin Grid Array (PGA). These pins fit into a socket layout called Socket 7. This meant that any processor would fit into any motherboard. Today, however, CPU manufacturers Intel and AMD use a variety of PGAs, none of which fit into Socket 7. As microprocessors advance, they need more and more pins, both to handle new features and to provide more and more power to the chip. Current socket arrangements are often named for the number of pins in the PGA. Commonly used sockets are: Socket 478 - for older Pentium and Celeron processors Socket 754 - for AMD Sempron and some AMD Athlon processors Socket 939 - for newer and faster AMD Athlon processors Socket AM2 - for the newest AMD Athlon processors Socket A - for older AMD Athlon processors The newest Intel CPU does not have a PGA. It has an LGA, also known as Socket T. LGA stands for Land Grid Array. An LGA is different from a PGA in that the pins are actually part of the socket, not the CPU. The chipset is the 'glue' that connects the microprocessor to the rest of the motherboard and therefore to the rest of the computer. On a PC, it consists of two basic parts -- the northbridge and the southbridge. All of the various components of the computer communicate with the CPU through the chipset. The northbridge connects directly to the processor via the front side bus (FSB). A memory controller is located on the northbridge, which gives the CPU fast access to the memory. The northbridge also connects to the AGP or PCI Express bus and to the memory itself. The southbridge is slower than the northbridge, and information from the CPU has to go through the northbridge before reaching the southbridge. Other busses connect the southbridge to the PCI bus, the USB ports and the IDE or SATA hard disk connections. Chipset selection and CPU selection go hand-in-hand, because manufacturers optimize chipsets to work with specific CPUs. The chipset is an integrated part of the motherboard, so it cannot be removed or upgraded. This means that not only must the motherboard's socket fit the CPU, the motherboard's chipset must work optimally with the CPU. A bus is simply a circuit that connects one part of the motherboard to another. The more data a bus can handle at one time, the faster it allows information to travel. The speed of the bus, measured in megahertz (MHz), refers to how much data can move across the bus. Bus speed usually refers to the speed of the front side bus (FSB), which connects the CPU to the northbridge. FSB speeds can range from 66 MHz to over 800 MHz. Since the CPU reaches the memory controller though the northbridge, FSB speed can dramatically affect a computer's performance. Here are some of the other busses found on a motherboard: The back side bus connects the CPU with the level 2 (L2) cache, also known as secondary or external cache. The processor determines the speed of the back side bus. The memory bus connects the northbridge to the memory. The IDE or ATA bus connects the southbridge to the disk drives. The AGP bus connects the video card to the memory and the CPU. The speed of the AGP bus is usually 66 MHz. The PCI bus connects PCI slots to the southbridge. On most systems, the speed of the PCI bus is 33 MHz. Also compatible with PCI is PCI Express, which is much faster than PCI but is still compatible with current software and operating systems. PCI Express is likely to replace both PCI and AGP busses. A motherboard's memory slots directly affect what kind and how much memory is supported. Just like other components, the memory plugs into the slot via a series of pins. The memory module must have the right number of pins to fit into the slot on the motherboard. Evolution: The original PC had a minimum of integrated devices, just ports for a keyboard and a cassette deck (for storage). Everything else, including a display adapter and floppy or hard disk controllers, were add-in components, connected via expansion slots. Over time, more devices have been integrated into the motherboard. It's a slow trend though, as I/O ports and disk controllers were often mounted on expansion cards as recently as 1995. Other components - typically graphics, networking, SCSI and sound - usually remain separate. Many manufacturers have experimented with different levels of integration, building in some or even all of these components. However, there are drawbacks. It's harder to upgrade the specification if integrated components can't be removed, and highly integrated motherboards often require non-standard cases. Furthermore, replacing a single faulty component may mean buying an entire new motherboard. Consequently, those parts of the system whose specification changes fastest - RAM, CPU and graphics - tend to remain in sockets or slots for easy replacement. Similarly, parts that not all users need, such as networking or SCSI, are usually left out of the base specification to keep costs down. The basic changes in motherboard form factors over the years are covered later in this section - the diagrams below provide a detailed look at the various components on two motherboards. The first a Baby AT design, sporting the ubiquitous Socket 7 processor connector, circa 1995. The second is an ATX design, with a Pentium II Slot 1 type processor connector, typical of motherboards on the market in late 1998. BIOS The All motherboards include a small block of Read Only Memory (ROM) which is separate from the main system memory used for loading and running software. The BIOS will most likely be stored in a 32-pin chip, which can typically be identified by a silver or gold sticker that shows the name of the BIOS company - such as AMIBIOS, AWARD or Phoenix - and a code that indicates the version of code it contains. If its rectangular in shape, it's what is known as a DIP (Dual In-line Package) chip. Older motherboards may have 28-pin DIP BIOS chips. If your BIOS chip is square with connections on all four sides, it is in a PLCC (Plastic Leaded Chip Carrier) package. The ROM contains the PC's Basic Input/Output System (BIOS). This offers two advantages: the code and data in the ROM BIOS need not be reloaded each time the computer is started, and they cannot be corrupted by wayward applications that write into the wrong part of memory. If you have a DIP or PLCC chip that's actually soldered to your motherboard, you'll not be able to upgrade it by replacing the ROM. Modern-day BIOSes are flash upgradeable, meaning they may be updated via a floppy diskette to ensure future compatibility with new chips, add-on cards etc. The BIOS comprises several separate routines, serving different functions. The first part runs as soon as the machine is powered on. It inspects the computer to determine what hardware is fitted and then conducts some simple tests to check that everything is functioning normally - a process called the power-on self test (POST). If any of the peripherals are plug and play devices, it's at this point that the BIOS assigns their resources. There's also an option to enter the Setup program. This allows the user to tell the PC what hardware is fitted, but thanks to automatic self-configuring BIOSes this isn't used so much now. If all the tests are passed, the ROM then tries to determine which drive to boot the machine from. Most PCs ship with the BIOS set to check for the presence of an operating system in the floppy disk drive first (A
, then on the primary hard disk drive. Any modern BIOS will allow the floppy drive to be moved down the list so as to reduce normal boot time by a few seconds. To accommodate PCs that ship with a bootable CD-ROM, some BIOSes allow the CD-ROM drive to be assigned as the boot drive. Some also allow booting from a hard disk drive other than the primary IDE drive. In this case it would be possible to have different operating systems - or separate instances of the same OS - on different drives. Many BIOSes allow the start-up process to be interrupted to specify the first boot device without actually having to enter the BIOS setup utility itself. If no bootable drive is detected, a message is displayed indicating that the system requires a system disk. Once the machine has booted, the BIOS serves a different purpose by presenting DOS with a standardised API for the PC hardware. In the days before Windows, this was a vital function, but 32-bit 'protect mode' software doesn't use the BIOS, so again it's of less benefit today. Windows 98 (and later) provides multiple display support. Since most PCs have only a single AGP slot, users wishing to take advantage of this will generally install a second graphics card in a PCI slot. In such cases, most BIOSes will treat the PCI card as the main graphics card by default. Some, however, allow either the AGP card or the PCI card to be designated as the primary graphics card. Whilst the PCI interface has helped - by allowing IRQs to be shared more easily - the limited number of IRQ settings available to a PC remains a problem for many users. For this reason, most BIOSes allow ports that are not in use to be disabled. With the increasing popularity of cable and ADSL Internet connections and the ever-increasing availability of peripherals that use the USB interface, it will often be possible to get by without needing either a serial or a parallel port. CMOS RAM Motherboards also include a separate block of memory made from very low power consumption CMOS (complementary metal oxide silicon) RAM chips, which is kept 'alive' by a battery even when the PC's power is off. This is used to store basic information about the PC's configuration: number and type of hard and floppy drives, how much memory, what kind and so on. The other important data kept in CMOS memory is the time and date, which is updated by a Real Time Clock (RTC). In modern-day PCs the nonvolatile BIOS memory is generally an EEPROM or Flash memory chip. EFI Intel first signalled that all that was about to change in early 2000, with the release of the first version of its Extensible Firmware Interface (EFI) specification, a proposed standard for the architecture, interface and services of a brand new type of PC firmware, designed to provide a well-specified set of services that are consistent across all platforms. EFI services are divided into two distinct groups, those that are available only before the operating system is loaded, known as 'Boot Services,' and those that are also available after EFI has assumed its minimum footprint configuration, known as 'Runtime Services.' Boot Services provide the breadth of functionality offered by EFI for platform configuration, initialisation, diagnostics, OS kernel image loading and other functions. Run-time Services represent a minimum set of services primarily used to query and update non-volatile EFI settings. The EFI specification is primarily intended for the next generation of IA-32 and Itanium architecture-based computers, and is an outgrowth of the 'Intel Boot Initiative' (IBI) program that began in 1998. Installing peripherals in a motherboard: To install these devices, you first need to open the computer and see what slots you have open. There are generally two kinds of expansion slots to put peripherals in: ISA and PCI. ISA slots are generally long and black and have a separator almost halfway between the ends of the slot. The PCI slot is either white or brown (generally a different color from the ISA slots) with a separator very close to one end. The card that fits in the ISA has two tabs, one smaller than the other on one side with gold metal strips (contacts) on the tabs. The PCI cards also have two tabs, but one tab is much shorter than the other. The short one only has about five gold contacts on it. Both types of cards have small components on them and a metal plate at one end with components connected to the plate. Communication Ports in Motherboard Ports are connectors used to connect external cables and devices to the motherboard. Motherboards that don't use integrated ports; they use headers on the motherboard instead. Headers are groups of pins used to connect devices or ports to the motherboard. A cable runs from the port and is plugged into the header on the board. Listed here, are few communication ports: Serial Ports: It is a male 9-pin or 25-pin port on a computer system used by slower I/O devices such as a mouse or modem. The name 'serial' comes from the fact that a serial port 'serializes' data. Parallel Port: This header has 26 pins. A parallel port is used for simultaneous transmission of data, one byte at a time but over multiple wires i.e. one bit per wire. This port on the back of the computer normally connects printers and scanners. PS/2 Mouse Port: Few motherboards provide a header for a PS/2 mouse port when this port is not already on the board. The PS/2 mouse header has 5 pins. USB (Universal Serial Bus): The USB technology is proposed to be the new standard for connecting devices such as keyboards, mice and other external devices to the PC. Some motherboards provide a 10 pin header to connect a port. Most of the present motherboards have built in USB ports. IR (Infrared) Port: Some motherboards have 4 or 5 pin headers to run a connection for an infrared communications port, typically used for wireless communication to IR devices. IR ports are very much common on laptops than desktop machines. Primary and Secondary IDE/ATA Hard disk Interface: Most of the new motherboards have integrated headers for two IDE channels. Each has 40 pins. Floppy Disk Interface: Most motherboards provide a 34-pin header for the floppy disk cable. SCSI: Few motherboards have integrated SCSI ports or headers, though they were uncommon, they are becoming increasingly popular. They are either 50 or 68 pins in size, depending on the type of SCSI implemented. Memory Slots on Motherboard Memory or RAM slots contain the actual memory chips. Memory slots are easy to identify on a motherboard. They are usually white; around 3 inch long, and placed very close to each other. The number of memory slots varies from motherboard to motherboard, but the appearance of the slots is very similar. There are metal pins in the bottom to make contact with the soldered tabs on each memory module. There are also small metal or plastic tabs on each side of the slot which we use to keep the memory module intact in its slot. The most common types of memory slots are SIMM sockets or DIMM sockets. The first type is for the older 72-pin SIMM-type memory. This type of memory needs to be installed in identical pairs, no mix & match. The two slots, that a pair of SIMMs go into is called a Bank. The current standard is DIMM socket memory. This is usually 168 pin 3 volt un-buffered synchronous DIMM-type memory. It is found in all newer Pentium II/III, Celeron, Athlon, Duron systems. This type of memory can be installed one stick at a time, and can often be matched with different types of DIMMs. Usually all the boards allow 384 to 512 MB of system RAM and few newer ones beyond 1 GB total system memory. There is another kind of slot called RIMM that uses only a 16-bit interface but run at higher speeds than DDR. To get maximum performance, Intel RDRAM chipsets require the use of RIMMs in pairs over a dual-channel 32-bit interface. Banks is a method by which a system addresses memory. A bank must be completely filled with memory modules of the same size and type in order for the system to recognize and address the memory. Following are memory slots based on number of banks. 3 (3 banks of 1) This indicates that there are 3 memory slots. These are divided into 3 banks, and each bank consists of one memory slot. So you can add memory one piece at a time for the system to use. 4 (2 banks of 2) This indicates that there are 4 memory slots. These are divided into 2 banks, and each bank consists of two memory slots. So you must add memory two pieces at a time (they must be the same size and type of memory) in order for the system to benefit from the upgrade. 12 (3 banks of 4) This indicates that there are 12 memory slots. These are divided into 3 banks, and each bank consists of four memory slots. So you must add memory four pieces at a time (and they must be the same size and type of memory) in order for the system to benefit from the upgrade. Riser architectures In the late 1990s, the PC industry developed a need for a riser architecture that would contribute towards reduced overall system costs and at the same time increase the flexibility of the system manufacturing process. new riser architecture specifications were defined which combine more functions onto a single card. These new riser architectures combine audio, modem, broadband technologies, and LAN interfaces onto a single card. They continue to give motherboard OEMs the flexibility to create a generic motherboard for a variety of customers. Two of the most recent riser architecture specifications include CNR and ACR. Intel's CNR (Communication and Networking Riser) specification defines a hardware scalable OEM motherboard riser and interface that supports the audio, modem, and LAN interfaces of core logic chipsets. The main objective of this specification is to reduce the baseline implementation cost of features that are widely used in the 'Connected PC', while also addressing specific functional limitations of today's audio, modem, and LAN subsystems. The CNR Specification supports the five interfaces: AC97 Interface - Supports audio and modem functions on the CNR card LAN Connect Interface (LCI) - Provides 10/100 LAN or Home Phoneline Networking capabilities for Intel chipset based solutions Media Independent Interface (MII) - Provides 10/100 LAN or Home Phoneline Networking capabilities for CNR platforms using the MII Interface Universal Serial Bus (USB) - Supports new or emerging technologies such as xDSL or wireless System Management Bus (SMBus) - Provides Plug and Play (PnP) functionality on the CNR card. ACR specification is supported by an alliance of leading computing and communication companies, whose founders include 3COM, AMD, VIA Technologies and Lucent Technologies. The ACR interface combines several existing communications buses, and introduces new and advanced communications buses answering industry demand for low-cost, high-performance communications peripherals. ACR supports modem, audio, LAN, and xDSL. Pins are reserved for future wireless bus support. Beyond the limitations of first generation riser specifications, the ACR specification enables riser-based broadband communications, networking peripheral and audio subsystem designs. ACR accomplishes this in an open-standards context. Latest motherboards in market The 915 and 925 chipsets are without doubt among the best on the market today from a technological standpoint. The 915P and 925X chipsets run an FSB clock speed of 200 MHz (termed FB800 because there are four data transfers per clock cycle). However, this past fall Intel introduced the 925XE chipset, which can run at an FSB clock speed of up to 266 MHz (FSB1066). Based on AMD's AM2 Socket processor, the M2R32-MVP motherboard supports the dual-channel DDR2 architecture. It provides higher memory frequency and bandwidth up to DDR2 800 for overall performance improvements over previous AMD CPU platforms. MSI€„¢s New 655 Max Motherboard Won the Honor of €œThe Fastest Pentium 4 Motherboard Ever Tested€? What To Look For when buying motherboard: The fastest pentium IV CPUs run at 800 MHz bus speed, and the fastest Athlon XP CPUs run at 400 MHz bus speed (both of these are in actuality 200 MHz multiplied 2 or 4 times by being double or quad pumped). The type of Chipset is the most important thing to consider in your motherboard. The chipset contains all of the motherboard's basic instructions, and also determines many of the motherboard's features. Hardware support is also quite important as you want your motherboard to support the hardware you are putting in it. Most of this will be determined by the chipset, but some will not, such as number of slots for memory expansion, number of PCI slots, number of USB and Firewire ports, and the presence of LAN, audio, and other possible onboard components. USB 2.0 and Firewire connectors come in handy for connecting peripherals. Onboard components used to be something to avoid, but they have improved lately. Getting an onboard network connector is usually helpful, and onboard audio is common now too. Onboard video is generally something to avoid though. Onboard audio generally isn't going to give you the best quality, but it's sufficient in most cases. With the nForce line of motherboards, the onboard audio is excellent. Another thing to consider is whether the motherboard comes with a cooling fan on the chipset. As speeds increase and chipsets become more complex, having good cooling becomes more important. While this isn't one of the most important things to consider, it is another sign of a good motherboard. The motherboard cost is often determined by the chipset being used. Obviously, you will want to get a motherboard that is going to last you awhile though. One key to doing this is to be sure your motherboard will support the newest CPUs.
