Motherboard

The motherboard in any computer is the main circuit board inside the box. Whether you own a laptop or a desktop computer, the motherboard is essential to the function of the computer. The motherboard is a printed circuit board also known as a PCB. The PCB with all the components attached is the PCBA or PCB assembly. The typical components of a circuit board are present with capacitors, diodes and resistors. These components connect the electrical circuit within the board and each component has a specific function within the circuit. The capacitors store an electrical charge and can keep constant power present despite power surges and sudden drops in power. The diodes are silicon chips that allow current to only pass through the circuit in a single direction. The resistors do just what they sound like in providing a specified amount of resistance to the electrical current. Circuit boards are double sided with a component side and a solder side to place the components and hold them in place. A motherboard itself is useless, but a computer cannot run without the use of the motherboard. Essentially the job of the motherboard is to hold the microprocessor and have all the computer components connect to the motherboard through a slot, port or socket. All contained on the motherboard is the CPU or central processing unit, BIOS or basic input output system, memory and storage.

The shape, size and layout of the motherboard is referred to as its form factor. Many form factors have been invented over the years, but there are a select few form factors which are typical to most motherboards on the market. There are many different form factors specific for large server computers and smaller motherboards for mini computers. As the motherboard gets larger or smaller it is intuitive on how much the motherboard can be expanded as there are a limited number of interfaces for cards or upgraded memory or capability. The most common form of motherboards is the ATX form factor which was developed by Intel in 1996. ATX stands for Advanced Technology Extended, with the board measuring 12”X9.6”. ATX replaced the now obsolete AT form factor to become the default for new computer systems. There have been several variations to the ATX board with similar capability in a smaller board. The sacrifice comes with less slots being available for expansion. In 2003, Intel introduced the BTX form factor to be the replacement to the ATX motherboard. As technology progresses, the power demands for components increased and so did the heat given off by the components. ATX is still the most popular form factor for do-it-yourselfer computer builders. If you are looking to replace your motherboard in your current box, make sure the motherboard matches up with the correct dimensions. A smaller motherboard may have to be installed if the size of the box constrains the motherboard which can be installed.

The microprocessor or CPU is a main component on the motherboard which determines the speed and performance of the computer. The faster the processor, the faster the computer can process instructions or think. The socket is the interface the microprocessor fits into where originally, the CPU connected through a PGA or Pin Grid Array. There are a plethora of CPU selections to choose from starting with the selection between Intel and AMD. There are many common sockets which have replaced the outdated technology.

AM2+ is the newest AMD socket on the market currently. It is very similar to its predecessor the AM2, but the main difference is the 2.6GHz HyperTransport speed versus the 1GHz speed of the AM2. The AM2+ also features split power planes with each dedicated to the CPU core and the other for the IMC or Integrated Memory Controller. The split plane allows the CPU to be in a sleep mode, while the IMC is still active which equates to better power management within the system. The aforementioned socket is Socket AM2, which was designed by AMD and released on to the market in 2006. The AM2 replaced Socket 939 and Socket 754. Socket AM2 is a PGA socket with 940 contacts and supports the AMD Athlon 64, Athlon 64 X2, Athlon 64 FX and Opteron Processors. The socket features memory support of DDR2-SDRAM and is a single processor socket. The front side bus or FSB is a 200MHz system clock with a 1GHz HyperTransport, which makes the system faster by replacing the typical FSB structure. Although it is unreleased at this point in time, socket AM3 is AMD’s newest socket which is due out late in 2008. The PGA socket is expected to support a DDR2 or DDR3 SDRAM type memory. In terms of compatibility, AM3 processors will work on AM2 motherboards, but not vise versa, as the AM2 chips lack the necessary memory controller for DDR3 memory. Computer enthusiasts will be able to upgrade to the AM3 on the current AM2 board, but not be able to enjoy the DDR3 memory. The advantages lie in the user being able to install faster processors into their system. The only true means to fully appreciate the AM3 is to have an AM3/DDR3 board.

Socket LGA 775 is one of Intel’s latest sockets to hit the market. Also known as Socket T, the LGA flip-chip works with the Pentium 4 chips, Dual Core, Xeon and Celeron processors. The Socket supports Dual channel DDR2 800/667 Un-buffered / Non-ECC memory. Socket 775 replaced Socket 478 because the LGA format of Socket 775 offers better power distribution versus the PGA Socket 478. The FSB speed is greatly increased to 1600 MT/s or Mega Transfers per second, which is exactly twice the transfer rate of the preceding Socket 478. The chips are less fragile with their LGA format and have increased heat dissipation qualities by allowing it to sit perfectly level with the internal heat sink.

Both of the sockets for Intel and AMD’s latest processors fit on all the ATX form factor boards and any smaller board which is based off the larger ATX board. These boards include, ATX, Micro ATX and Mini ITX which are the most popular and common form factors on the market for computer enthusiasts.

The motherboard connects the different functions of the microprocessor to the rest of the computer through the use of a north and south bridge. The northbridge is connected directly to the processor and connects components and slots needing the highest amount of processor speed necessary to operate at their optimum level. The front side bus or FSB connects the processor to the northbridge. The southbridge is slower than the northbridge and connected to the southbridge are the slots which do not require faster processor speeds. Information must pass through the northbridge before reaching the southbridge.

Bus speed determines how quickly a circuit board can connect one part of the motherboard to the other. The bus speed is measure in megahertz or MHz and this speed will tell the user how much data can move simultaneously through the bus. When reading bus speed on a specification sheet, this is usually referring to the FSB or front side bus, which connects the northbridge and processor together. When selecting a motherboard, again knowing the desired function of the completed computer system is essential. The AGP or Accelerate Graphics Port connects the video card to the memory module and the processor. Gaming without any kind of hitch in the action is facilitated by having a high bus speed in the AGP.

PCI or Peripheral Component Interconnect is how you would add different cards to the computer or expand your PC. PCI was the standard for adding any kind of additional sound or video graphics card to your computer. These are your expansion slots. Because PCI is more of a general purpose expansion connection, the newer cards requiring higher bandwidth have also been form fitted to fit specified interconnects on the motherboard. The AGP or Accelerated Graphics Port is like the PCI interconnect in that it is a point to point channel specifically installed on a motherboard to interface with a high-end graphics card. Because there are typically more than one PCI interconnect on a motherboard, the AGP provides a dedicated access between the port and the microprocessor, which makes communication between the card and processor much faster. AGP has recently been replaced with PCI Express which was designed to completely replace PCI and AGP. PCI e does not structure itself around a bus speed, but uses a serially linked full duplex point to point system called, lanes. There can be up to 32 lanes of data dedicated to the PCI e and the motherboard. This allows for extremely fast data transmission. The fastest potential speed is 8 GB/s but the fastest available speed at this time is 4 GB/s. For serious gamers, and high graphic necessity, the PCI e is essential when selecting a motherboard. For enhanced 3D graphics, NVIDIA’s SLI or Scalable Link Interface allows the user to link two or more video graphics cards together. More than one PCI e slot is needed to have this capability as well as an Intel processor. Crossfire made by ATI is a competitor of NVIDIA’s SLI and can link up to four graphics cards together. The advantage with ATI is that they have opened the architecture to Intel after it was designed for AMD. SLI requires an SLI certified motherboard, while ATI simply requires more than a single PCI e slot. ATI has a higher bandwidth, but a slower clock speed. ATI’s Crossfire is not available for notebooks, where SLI is available for notebooks. Proper research, desired functionality and performance must first be ascertained before building the motherboard. Start with the desired processor only after investigating what components are supported by the processor.

Integrated Drive Electronics or IDE and Advanced Technology Attachment or ATA are interchangeable terms used to describe the port at which storage devices are connected to such as hard disks and CD-ROM drives. These drives are among the most primitive of the connections to a motherboard as the ribbon used to connect the drives was first developed in 1986. The cables or ribbon are in two varieties of a 40 wire or an 80 wire ribbon which connect the drive to the interface. Typically, a mother board will have two or more interfaces to connect these peripheral devices. The IDE or ATA is controlled by the southbridge as the speed needed to process the information is comparatively low. Each interface can handle two devices of the like. Many new computers have two CD-ROM drives where one can act when the other one is not.

Both of these drives are connected to the same ribbon and attach to the interface. The master slave relationship is described as the slave drive checking if the other drive or master drive is in use. If the master is not in use, the slave will operate. When setting up a second CD-ROM drive, the computer will ask the installer if the drive being installed is a master or a slave. Choose accordingly to what drive is which. When installing one drive, most situations require that the drive be a master.

There are several other components to determine the speed of your computer aside from the processor speed. The amount of RAM or random access memory present in your computer is a large determinate of how quickly your computer can access information in no particular order, or at random. There are several different types of RAM and motherboards will come with expandable memory slots where more RAM can be added to your computer. Should the computer become low on RAM, the computer will then begin using hard drive space for additional memory, which slows computer performance. Memory is usually bought in the form of DRAM or Dynamic RAM which is structurally much more simple than Static RAM or SRAM, but DRAM requires a capacitor refreshing, as capacitors lose charge over time and the memory will also fade. When purchasing additional RAM, the buyer is typically purchasing DRAM. The pieces of DRAM are about the size of several sticks of gum and are easily inserted into the slots where your computer will immediately have an increase in performance.

The only real visible portion of the motherboard from the exterior of the computer box is usually in the rear with the connections to the various peripheral devices. The ports are soldered directly to the motherboard and they connect your mouse or keyboard to the motherboard. Serial and parallel ports will connect a printer for example, where the serial can be used to connect a joystick for gaming purposes. This was the old standard, and most gamers hook up their peripheral devices to the USB ports. Although most computers come equipped with parallel ports, most peripheral devices can be hooked to the computer via USB. Your phone cable line and Ethernet cable hookup, as well as the various USB ports are also soldered directly to the motherboard. If you plan on attaching a high definition audio video device to your computer, the consideration of a Firewire or IEEE 1394 High Speed Serial Bus might want to be considered. The Firewire is preferred over USB because the Firewire has greater speed, higher sustained data transfer and power distribution capability and does not need a computer host. This equipment is very standard with all motherboards. The most important features to look for are of course the processor speed and what kind of expansion slots are available to upgrade the computer for specific needs. There is a lot of information which goes into selecting a motherboard, but with the proper research and knowing the desired performance and functionality, the average computer enthusiast can build himself a powerful computer with excellent capability.