Now the fun really begins as we start looking at the bits of the PC that you normally never see, and we'll begin with the system motherboard. The motherboard, also called the mainboard, is the large printed circuit board which is the elecronic hub of your PC. Not only does this circuit board host the Central Processing Unit, or CPU, which is the brains of the computer, it also either hosts additional plug in process cards or has features that can come on plug-in cards actually built into the motherboard itself. More on this in a minute.
Let's start by having a look at a typical motherboard. This one is for an Intel Pentium 4 CPU and the CPU chip will plug into the Socket 478 Connector at the top center of the board (more on CPU chips again). Next we would have the memory chips or RAM (random access memory)plugged into the vertical blue and black slots in the upper right section of the board (labelled DDR DIMM Memory Slots - DDR DIMM stands for double data rate dual in-line memory modules, we love our acronyms in the PC business!).
Many of the features we find on a modern PC, such as an Ethernet port to connect to a local area network, a modem to dial into a network, sound capability to allow music and sounds to be heard, graphics capability to permit us to see our system on a monitor, used to require separate expansion cards which were plugged into expansion slots on the motherboard. So, if you wanted to dial into the Internet you would have had to physically install a modem in one of the five white horizontal PC slots you can see in the bottom left of the board. With the advances in motherboard design in recent years you can now find motherboards with all the extras built in, leaving the PC slots more or less redundant for many users. A function that used to require a separate expansion card in the past has been minaturized to just one more chip integrated into the motherboard. However, not all functions have yet been integrated into the motherboard so, for example, if you want a PC that can display TV on your monitor, you will need to add a TV tuner card to one of your PCI slots, like one of the ones in the picture. Also, some of the funtionality integrated into motherboards is often quite basic, a good example being the graphics processing capability built into many motherboards. The onboard graphics chip will display your screen perfectly adequately for 2-D applications, such as your word processor or web browser. However, these are generally completely inadequate for playing 3-D games of the type that are common today. While some of these games may run, they will run very slowly or jerkily and the experience will be frustratingly poor. Because of this a whole market has arisen in add-in graphics cards and these are plugged into the brown horizontal slot, above the PCI slots, labelled AGP 8X Slot (AGP = accelerated graphics port).
The optical drives (CD or DVD) in the front of your PC are connected to the blue and black IDE connectors on the right side of the board by flat ribbon cables, normally grey in colour. The floppy disc drive, if you have one, is connected by a similar cable to the FDD Connector, again on the right side of this board.
Power is brought to the board by means of two connectors that extend from the power supply unit (PSU). These are plugged into the ATX Power Connector (beside the FDD Connector) and the 12V ATX Power Connector at the top left of the board.
The Back Panel Connector (top left edge of board) contains the only part of the motherboard that you are likely to see from time to time. This is the collection of sockets that you connect your mouse, keyboard, monitor, printer, and various USB devices to and this protrudes through a slot at the rear of your system case, like in the picture. You should note that while the motherboard in your PC will have all of the elements that I have highlighted they may be in a completely different location than in the example above. There are thousands of different motherboard designs and each manufacturer will lay out the components on the board differently.