The motherboard "is" the computer. It is what connects everything together. The motherboard holds the RAM, the CPU, all of the expansion slots, and many other key components.

There are three different sizes of motherboards: Baby AT, AT, and ATX. The size corresponds to the smallest size of the computer case that the motherboard can fit in.

Motherboards vary greatly in design and features. When buying a motherboard, you must first make sure that it will fit in your case and that it will be compatible with the particular CPU that you plan to use. The motherboard's CPU socket should match the socket type of your CPU. The motherboard should also accommodate the CPU with the right kind of bus frequency and voltage. While this is usually not a major concern as motherboards can accommodate a wide range of frequencies and voltage, it is best to contact the motherboard manufacturer if you are not sure of this information. Next, make sure that the motherboard has enough expansion slots to fit all of your cards. All expansion slot devices use one of three hardware interfaces (PCI, ISA, or AGP), so ensure that the board has enough of each. Third, make sure that the motherboard supports the type of RAM that you will use. It should accommodate either DIMMs or SIMMs (please see the memory page for more information). Motherboards range in price from about $50 to $500. The more expensive ones have multiple CPU sockets and SCSI controllers built in.

The motherboard is somewhat complex to install; about an hour is required. A motherboard can be installed using only a Phillips screwdriver, but we also recommend a jumper-puller and a flashlight.
 

the installation

1. Make sure that your computer is turned off.

2. Carefully disconnect the cables from the back of the computer, place the computer on a stable working platform, and remove the case. Discharge any static electricity in your body by touching the computer's power supply.

3. Disconnect all of the cables from the old motherboard. Remove all expansion slot components.

4. Depending on the layout of your case, you may need to remove the motherboard tray to gain access to the motherboard (usually only with tower cases). To remove the tray, you may need to remove some screws surrounding it before you pull it out. Either way, once you have access to the motherboard, proceed to the next step.

5. Remove the plastic motherboard standoffs and unscrew the motherboard from any metal standoffs. Lift the motherboard off the standoffs. Take care not to use a magnetic screwdriver to unscrew the screws as essential pieces of equipment may be damaged.

6. Line up the holes on the motherboard with the holes on the tray. Do not place any extra screws under the motherboard for "support" because they may cause a short circuit. Screw in the spacers in the appropriate holes, and then place the motherboard on top and screw it in.

7. Remove the CPU and RAM from the old motherboard, and then install them on the new one. For further instructions, go to the core menu and select the appropriate component.

8. Compare the holes in the motherboard to the corresponding holes in the case and take note of the ones that match. Push the previously removed plastic standoffs into the matching holes on the case (or tray, if applicable).

9. Carefully slide the motherboard onto the standoffs and snap it into place. If there aren't enough plastic standoffs to support the entire motherboard, screw in the included metal ones as well.

10. Replace the motherboard tray (if applicable), and then install all of your expansion slot components. Be sure that all internal cables (including the power switch, reset button, power indicator, and hard disk activity indicators) are reconnected. Replace the computer's outer case and move the computer back to its original location. Reconnect all of the external cables.

11. Start up the computer. If it does not boot properly, go back through the installation steps and recheck all cables.