The motherboard is the main circuit inside every computer. It connects every other component. Below is a brief diagram explaining where other components connect.
The CMOS battery maintains a small current through the motherboard so that certain BIOS settings can be stored even whilst the PC is not plugged in. A symptom of a flat CMOS battery is that your computer forgets the time when it is turned off. The batteries are usually straight forward to replace. The battery is usually a CR2032, but it's best to check yours first to be sure. A flat CMOS battery is usually only found in aged or faulty motherboards.
Near the CMOS battery there is usually a 'CLEAR CMOS' jumper (it is usually printed on the circuit board). In this image, it is the red pice of plastic on the near side of the battery. A jumper is a set of two or more pins that can be crossed to change a setting. You shouldn't touch jumpers unless you know what they are for and what you are doing. Crossing the 'CLEAR CMOS' jumper will restore all BIOS settings (such as time, installed drives, clock speeds etc.) to their default values. This can sometimes fix some issues, but make sure that you know how to set the BIOS back up to the required settings.
The CPU (Central Processing Unit, otherwise known as the processor) is where most of the work your computer does will take place. Different motherboards will accept different processors. Usually incompatible processors won't fit in the motherboard, but some variatons of some processors won't work in all motherboards. It's always best to check compatibility before buying a processor (or motherboard) by reading the motherboard manual or specs which can usually be found online.
The processor usually has a large heatsink and fan attached to it which connects to the motherboard near by. This is because the processor generates a lot of heat which would quickly cause damage if it wasn't dispersed. A common cause of fault in computers is dust clogging this and other fans. This will usually cause noise and overheating. As well as the noise, a common symptom of overheating is the computer powering itself down after it has been on for a while. The fan and heat sink are usually clamped on to the top of the processor. In between the heatsink and the processor there should be a thin layer of thermal paste. This paste helps remove heat from the processor more efficiently. If the heatsink and fan are removed, old thermal paste should be removed and a new layer should be applied.
Upgrading the processor can be a cost effective way of improving your computers performance, especially for older, single core systems as these processors are cheaply available online. To remove the old processor: -
All fairly recent motherboards require a power supply with a 12V four pin connector to power the processor. Older power supplies won't have them, but adapters can be bought cheaply online (check here) or you can add a connector yourself (obviously at your own risk!). If you do not connect this plug, the computer will act as though it is powering up (lights and fans will activate), but you will get no display on the screen (except for maybe a warning on some motherboards).
This is where the PSU (Power Supply Unit) connects to the motherboard. Modern motherboards may accept a 24 pin connector where as older motherboards only accept a 20 pin connector. Power supplies usually come with the last four pins being detachable so that they will work on both types motherboards. In my experience, a 20 pin connector will still work fine in a 24 pin motherboard, but I expect that the set up will only perform at its best with the 24 pin power supply connected.
A damaged or faulty PSU can cause damage to anything connected to it, which is everything! If you suspect a PSU is misbehaving, it's worth while checking out inexpensive power supply testers on eBay (click the link). Such a tester might save you the price of a new motherboard and more.
This is where you can connect CD, DVD, Blu Ray, Floppy Disk and Hard Drives. The smaller connector is for the floppy disk drive, which, although near redundant now is very handy for installing SATA drivers when installing operating systems. SATA drives are the new standard and use a different, smaller connection. They are faster and use tidier wires, but as previously stated, currently need drivers. Drivers are small pieces of software that tells the operating system how to communicate with devices. In future, operating systems are likely to have these drivers already built in, but at present they are usually required to be installed via a floppy disk whilst the operating system is being installed.
IDE drives connect via a ribbon of cables, usually with three connectors. One connector connects to the motherboard and the other two connectors connect to the drive(s). If more than one drive is installed on the same ribbon, one must be set as a 'Master' and the other as a 'Slave' (or both as 'Cable Select', but this won't always work). This simply allows the motherboard to distinguish between the two (like assigning them both different names). To set one as a 'Master' or 'Slave', you usually have to adjust the jumpers near the connector on the drive. Instructions should be clearly printed or inscribed on the drive itself. SATA drives do not require this adjustment.
This is where you will connect your keyboard, mouse, speakers*, monitor*, modem* / router* etc. *=dependant on motherboard models, some wil not have the mentioned connections onboard. None of these connectors are vital as they can be replaced using PCI cards (see below), so if one breaks, you can buy a PCI card to replace it.
This is where you will install your RAM. RAM is where your computer keeps track of what it is currently doing. When you turn your computer on, for example, you wait while your operating system loads up. This is where it loads to as does any other application or file that you use.
Upgrading the RAM in a computer is without doubt the most cost effective way of improving a computer's performance. In the early days of XP, some XP computers were sold new, with only 128Mb of RAM. Upgrading this to 512MB or more would make it run like a totally different machine and may cost less than £10! The minimal amount of RAM I would reccommend for Windows XP is 512Mb, but 1Gb would be better. For Vista I would reccommend no less than 1Gb and would personally want no less than 2Gb.
Motherboards with built in graphics (there's a monitor connector on the external connections) will share whatever RAM you have installed with the graphics. The amount shared usually ranges between 16Mb to 256Mb depending on how recent the motherboard is. If your motherboard is sharing memory, you can usually change the amount in the BIOS settings. I would reccommend sharing as around 16Mb - 32Mb, unless you play games in which case you should buy a graphics card and disable the onboard graphics all together.
.Faulty RAM can be the cause of frequent crashes or even failure of the PC to start up at all. Replacing or upgrading RAM is simple as long as you know what RAM to buy. There are tools and websites available to help with this, but if you have your motherboard manual, it will clearly state what RAM is compatible. If you don't have the manual, try searching online for your motherboard's model number or manufacturer. To remove a stick of RAM, press down the clip at either end of the stick and it will become loose. Just take it out. To insert a new stick, make sure that it is correctly aligned with the slot, checking that the gaps on the stick correspond with the gaps in the slot. Make sure that the catches are up and open and push the RAM into placeat one end and then the other. As each end is pushed in, the catches will close. You shouldn't have to push too hard, so if it's not going down, double check that it is correctly aligned.
These slots are for expansions to you computer. You can use them to add a sound card, a graphics card, extra USB of FireWire ports and more. How you install PCI cards will depend on the type of case your motherboard is housed in. Usually there will be metal plates screwed in front of empty PCI slots which can be easily removed. Once removed, the PCI card can be installed and screwed down. Some cases will have clips or catches that must be released or removed in order to remove or install a PCI card.
Most reasonably recent motherboards will include a special slot for graphics cards. The oldest of these (as above) will include an AGP slot and will only accept AGP graphics cards (or PCI graphics cards in a PCI slot). The newer motherboards have a longer, PCI-E (PCI Express) connector. These connections are potentially faster and can also be used for other types of card such as Sound. Some motherboards will have more than one PCI-E slot and may be SLI or CrossFire compatible which allows the use of more than one graphics card at once in a special set up (with compatible cards) offering more powerful performance.
Where these slots are available, I would reccommend using them, even if it is with a cheaper graphics card. Doing so will usually increase the performance of your computer as it often frees up RAM and takes some of the workload from the processor. Graphics cards are installed in the same way as PCI cards, but some have a small catch at the back end which must be engaged to install or remove the card. Reasonably powerful graphics cards will require a direct connection to your power supply. When using these cards, it's reccommended to have a 400 Watt power supply or higher. The connection type can vary and a special adapter may be required (check here).
