The motherboard is probably the most complex PC component to upgrade, but modern operating systems and standards have taken much of the pain out of the process. Even so, ancillary issues such as software activation now make the task more – rather than less – annoying than before.
Before choosing a motherboard, you need to understand the purpose of the system you're upgrading or building. If it will be small in volume, you'll want to use a micro ATX or mini ITX board. If you're planning to overclock, you'll want to incorporate a board that offers robust voltage regulation and good cooling over those voltage regulator modules (VRMs). And if you're looking to build an office PC, you'll want to ensure it has built-in video output connectors.
Other complications exist, particularly if you're upgrading an Intel-based system. Intel now has four active socket formats: LGA775, LGA1156, LGA1366 and LGA1155. If you'll also be upgrading your existing processor, you'll need to confirm that your motherboard has the correct socket for it. Upgrading an AMD CPU is a little easier as most socket AM3 boards support all AMD processors.
Check the size and capacity of your existing system case. If it supports ATX motherboards, anything ATX-size or smaller will fit. If you have a BTX-format case, it will probably also support ATX motherboards, but you should check with the manufacturer to make sure. Extended ATX (eATX) boards are larger than ATX models, but these are rare and are usually workstation-class boards that support more than one processor.
See also: How to upgrade a PC's processor
Set up a workspace that offers adequate lighting. Good lighting is critical if your case has an all-black interior. Give yourself enough room to lay out tools and parts.
Prior to disassembling the system, back up the contents of your hard drive. See How to back up a PC.
Collect all your licence keys. Deactivate or deauthorise any programs that you previously activated. This includes Apple iTunes and Adobe professional programs (such as Photoshop and Premiere CS5). You should also uninstall or deactivate any games that required activation.
Determine which PC components need to be removed. You may have to take out the power supply unit (PSU) or hard drive to make motherboard removal easier.
If you have to remove the PSU, take care to disconnect all its power cables first. The ATX12V (a small four- or eight-pin connector) is easy to overlook.
Now remove all the add-in cards, the processor fan and any memory modules. If you're not upgrading the processor, you can leave it in its socket for the moment.
Disconnect all the wiring. Double-check that you've done so correctly.
Remove the screws holding the motherboard in place. Place the old motherboard in an antistatic bag.
Check all the mounting nuts are firmly screwed into the case. These can become loose when you remove the motherboard.
Remove the ATX I/O shield, and store it with the old motherboard. Now install the ATX I/O shield shipped with your upgrade. This step is crucial. It's also frustrating to have screwed in the motherboard and only then find that you forgot the I/O shield.
If you're using an exotic cooler, it may require a special support plate to be attached to the underside of the motherboard.
Line up the I/O ports with the holes in the ATX I/O shield and align the screw holes with the motherboard mounting nuts on the interior of the case. Carefully screw in the mounting screws. Do not overtighten them. If you have an electric screwdriver equipped with an adjustable clutch, set the clutch to the minimum setting. If your electric screwdriver doesn't have a clutch, use a hand screwdriver instead.
If you removed it earlier, reinstall the PSU. Next, reinstall any storage devices you may have removed.
Reattach the wiring and cables you disconnected earlier: front panel connectors, USB wiring for the USB case connectors, power cables, wires for the case fan and so on. If your case allows you to route wiring behind the motherboard, do so now.
Also attach the power cables, taking care to connect both the main and the ATX12V cables.
Install the CPU (if you had to remove it earlier) and the memory. Don't install the CPU cooler until after you've installed the memory and the power connectors.
Plug in the data cables and attach the power connectors to the storage devices. Reinstall any cards you removed. If you're also upgrading the graphics card, be sure to attach the PCI Express power connectors.
Connect wall power, the video cable, the mouse and the keyboard, and give the system a test boot. If nothing happens, make sure the PSU switch is on.
When you boot up the system, you'll need to wait while Windows accounts for all the motherboard devices. Your keyboard and mouse may be unusable during this time. Once Windows has logged each of the devices, reboot the PC.
Take the CD supplied with your motherboard and install the board, network, USB 3.0 and video drivers (the latter only if you're using integrated graphics). You may need to reboot the PC several times.
Once you've done all this, check to see whether Windows needs to be reactivated. If so, first try activating it over the internet. If this fails, call the freephone number listed in the Activation Window. If you do activate over the phone, be sure to tell Microsoft that you're installing this copy of Windows on one system. This is just an upgrade after all.
Reinstall and reactivate any applications you need, then get computing.