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Features of the motherboard
Every PC has basically the same hardware. The differences in the size and power of microprocessors and memory capacity are the main factors that make one PC more expensive than another.
The motherboard
When you open the case of a computer, the large rectangular circuit board which you can see is the 'motherboard' (sometimes called the 'system board' or 'main board'). The motherboard forms the foundation of the computer system.
The motherboard, or main-circuit board, is the largest board located in the bottom or at the side (in a tower case) of the system case. All the hardware is connected to the motherboard in some way and is able to communicate with the CPU (Central Processing Unit). Bus lines, expansion slots and I/O ports allow the CPU to be connected to a variety of hardware, expanding the capabilities of a computer system.
Identifying common parts of the motherboard
The CPU
The Central Processing Unit, or CPU, is the brains of the computer and is responsible for controlling the flow of data throughout the computer and for executing program instructions.
The microprocessor, or CPU, is a computer chip which plugs into a special socket on the motherboard and can be removed or replaced easily.
There are several manufacturers of microprocessor chips, the major two being INTEL and AMD. In general, most motherboards can accept chips from either manufacturer; however some boards are designed specifically for one type of chip only.
The operating speed of the CPU is one of the most critical factors in the computer's processing power.
The Speed of a CPU
All microprocessors are not created equal. They vary in the speed at which they carry out their tasks and the volume of tasks they can do.
The speed of the CPU is controlled by the electronic clock that is connected to it on the motherboard. This clock generates electrical 'ticks' millions of times every second. The number of ticks is called the clock speed of the computer.
Because one tick is actually an electrical cycle, clock speeds are measured in millions of cycles per second—megahertz (MHZ), or 1 thousand million cycles per second—gigahertz (GHZ). The faster the clock speed, the faster the computer can process data.
Memory
Memory is a critical component of all computer systems and comes in the form of blocks of integrated circuit chips. Although there are two types of memory in all computers (RAM and ROM), the term 'memory' is used to indicate the amount of temporary storage (RAM) that the computer has installed. More RAM can be easily added to the system to increase its temporary storage capacity, and consequently, its processing power.
- RAM (Random Access Memory)
- ROM (Read Only Memory)
NOTE: There is also a third type of memory known as 'Read/Write memory'. This is the type of memory used to store and retrieve data.
RAM
Random Access Memory (RAM) is the CPU's memory or workspace. Software you want to work with is loaded from the hard disk drive into RAM. RAM is short term memory. When the power is turned off, any data in RAM is lost. Because of this loss of data, RAM is said to be 'volatile' memory.
RAM is measured in terms of how many characters it can contain. The technical term for this character is a byte.
The amount of RAM installed in a computer is usually stated in megabytes for older computers that had limited amounts of memory or in gigabytes for more modern computers.
The amount of RAM in the computer affects the size and number of programs that it can execute. Additional RAM can be added into a computer by directly inserting additional memory chips, or by installing a circuit board containing additional memory chips. On most new PCs, 512 MB of RAM should be sufficient, and 1 GB is the best for graphics/video editing. The most common type is DDR RAM, while RD (Rambus) memory is gaining popularity.
ROM
Read Only Memory (ROM) is a form of memory which could be said to be 'locked'. With ROM, data or programs are written to the component at the time of manufacture, and are retained permanently, even if the power to the computer is turned off. For this reason ROM is called non-volatile memory.
The BIOS (Basic Input and Output System) chips on the motherboard are an example of ROM.
At start up, the system memory is empty. The computer needs instructions from the BIOS chip to tell it what processes need to be initiated to make the computer operate.
Bus
A bus is a pathway of wires and connectors which provides the link between the input, output, processing and storage and control devices. That is, the bus allows the CPU to transport data to and from memory, receive input from external devices, and send output to external devices. In addition to the data, a bus also carries the addresses of the source and destination of the data.
On the motherboard, they are fine, metallic strips etched on to the board. At the place at which they leave the motherboard, they are replaced by a ribbon, or cable, of fine wires in order to connect to other devices, such as a disk drive.
Expansion slots and cards
When PC users need to increase their computer's functionality, they can add new features to the processing hardware through expansion slots on the motherboard. Expansion slots are designed to link the processor and existing memory to circuit boards or expansion cards, which support new computing options. Expansion cards are available for increasing memory, adding 3D graphics, connecting to a fax machine, providing multimedia capabilities like sound and video I/O and installing cache memory. Personal computers will have from three to eight expansion slots on the motherboard. Installation of new expansion cards is quite easy. For example, users wishing to add 3D graphics need only purchase a 3D graphics adaptor board and slip it into an expansion slot. New expansion boards are often accompanied by a disk containing a related device driver. The driver must be installed on the system disk. The new graphics capabilities become immediately available after rebooting the computer, although related software packages sometimes need to be installed again.
Cache memory
Cache memory is information from recently accessed data that is stored so other computers which need the same data can access it immediately. For example, proxy servers cache recent downloads from the internet. When you want to access this information at a later time the same downloads come instantly from the proxy server, rather than having to be slowly downloaded again from the original site.
The website ‘PC World’ has some great information on motherboards at:
http://www.pcworld.idg.com.au/index.php/id;641784313 
The following website has some excellent information on the internal components of a computer. Go to:
http://www.howstuffworks.com/motherboard.htm There are some excellent photos and brief explanations of the motherboard components.
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