Section 4.4. Replacing a Motherboard

4.4. Replacing a Motherboard

The exact steps required to replace a motherboard depend on the specifics of the motherboard and case, the peripheral components to be connected, and so on. In general terms, the process is quite simple, if time-consuming:

  • Disconnect all cables and remove all expansion cards from the current motherboard.

  • Remove the screws that secure the old motherboard and remove the motherboard.

  • If you are reusing the CPU and/or memory, remove them from the old motherboard and install them on the new one.

  • Replace the old back-panel I/O template with the template supplied with the new motherboard.

  • Remove and install motherboard mounting posts as necessary to match the mounting holes on the new motherboard.

  • Install the new motherboard and secure it with screws in all mounting hole positions.

  • Reinstall all of the expansion cards and reconnect the cables.

The devil is in the details. In the rest of this section, we'll illustrate the process of installing the motherboard and making all the connections properly.


In this sequence, we'll assume that you have already populated the motherboard by installing the processor and CPU cooler (Chapter 5) and the memory (Chapter 6). With very few exceptions, it's easier and safer to install the processor and memory before you install the motherboard in the case.

4.4.1. Getting started

Before you start tearing things apart, make sure you have at least one good backup of all your important data. You needn't worry about backing up Windows and applicationsalthough you should, if possible, back up the configuration information for your mail client, browser, and so onbecause unless you're replacing an old motherboard with an identical new motherboard, you may need to reinstall Windows and all applications from scratch.

Disconnect all cables and external peripherals from the system, and move it to a flat, well-lighted work areathe kitchen table is traditional, as we mentioned earlier. If you haven't cleaned the system recently, give it a thorough cleaning before you begin work.


Although by necessity we describe a particular sequence for installing the motherboard, you don't need to follow that sequence if it makes sense to depart from it. Some steps, such as installing expansion cards after you install the motherboard in the case, must be taken in the order we describe, because completing one step is a prerequisite for completing another. But the exact sequence doesn't matter for most steps. As you install the motherboard, it will be obvious when sequence matters.

Remove the access panel(s) from the case, disconnect all of the cables from the motherboard, and remove all of the screws that secure the motherboard to the case. Ground yourself by touching the power supply. Slide the motherboard slightly toward the front of the case, lift it straight out, and place it aside on the table top or another nonconductive surface.

4.4.2. Preparing the case

Removing the motherboard may expose more dirt. If so, use a brush and vacuum cleaner to remove that dirt before you proceed further.

Every motherboard comes with a back-panel I/O template. Unless the current template matches the port layout on the new motherboard, you'll need to remove the old template. The best way to remove an I/O template without damaging it (or the case) is to use a screwdriver handle to press gently against the template from outside the case, while using your fingers to support the template from inside the case until the template snaps out. If the old motherboard is still good, put the old template with it for possible use later.

Compare the new I/O template with the back-panel I/O ports on the new motherboard to make sure they correspond. Then press the new template into place. Working from inside the case, align the bottom, right, and left edges of the I/O template with the matching case cutout. When the I/O template is positioned properly, press gently along the edges to seat it in the cutout, as shown in Figure 4-15. It should snap into place, although getting it to seat properly sometimes requires several attempts. It's often helpful to press gently against the edge of the template with the handle of a screwdriver or nut driver.

Figure 4-15. Press the new I/O template into place

A Little Flexibility May Be a Bad Thing

Be careful not to bend the I/O template while seating it. The template holes need to line up with the external port connectors on the motherboard I/O panel. If the template is even slightly bent, it may be difficult to seat the motherboard properly.

After you install the I/O template, carefully slide the motherboard into place, making sure that the back-panel connectors on the motherboard are firmly in contact with the corresponding holes on the I/O template. Compare the positions of the motherboard mounting holes with the standoff mounting positions in the case. One easy method is to place the motherboard in position and insert a felt-tip pen through each motherboard mounting hole to mark the corresponding standoff position beneath it.


If you simply look at the motherboard, it's easy to miss one of the mounting holes in all the clutter. We generally hold the motherboard up to a light, which makes the mounting holes stand out distinctly.

Remove any unneeded brass standoffs and install additional standoffs until each motherboard mounting hole has a corresponding standoff. Although you can screw in the standoffs using your fingers or needlenose pliers, it's much easier and faster to use a 5 mm nut driver, as shown in Figure 4-16. Tighten the standoffs finger-tight, but do not overtighten them. It's easy to strip the threads by applying too much torque with a nutdriver.

Figure 4-16. Install a brass standoff in each mounting position

Don't Miss Any Standoffs

Make absolutely certain that each standoff matches a motherboard mounting hole. If you find one that doesn't, remove it. Leaving an "extra" standoff in place might cause a short circuit that could damage the motherboard and/or other components.

Once you've installed all the standoffs, do a final check to verify that each motherboard mounting hole has a corresponding standoff, and that no standoffs are installed that don't correspond to a motherboard mounting hole. As a final check, we usually hold the motherboard in position above the case, as shown in Figure 4-17, and look down through each motherboard mounting hole to make sure there's a standoff installed below it.

Figure 4-17. Verify that a standoff is installed for each motherboard mounting hole and that no extra standoffs are installed

Pen and Ink

You can also verify that all standoffs are properly installed by placing the motherboard flat on a large piece of paper and using a felt-tip pen to mark all motherboard mounting holes on the paper. Then line one of the marks up with the corresponding standoff and press down until the standoff punctures the paper. Do the same with a second standoff to align the paper, and then press the paper flat around each standoff. If you've installed the standoffs properly, every mark will be punctured, and there will be no punctures where there are no marks.

4.4.3. Seating and securing the motherboard

If you have not already installed the processor and memory on the motherboard, do so before proceeding. See Chapters 5 and 6 for detailed instructions.

Slide the motherboard into the case, as shown in Figure 4-18. Carefully align the back-panel I/O connectors with the corresponding holes in the I/O template, and slide the motherboard toward the rear of the case until the motherboard mounting holes line up with the standoffs you installed earlier. You may need to tilt the motherboard slightly down towards the I/O template to slip the back-panel connectors easily under their corresponding grounding tabs without damage. Make absolutely certain that none of the grounding tabs intrude into the jacks on the I/O panel. USB ports are particularly prone to this problem, and a USB port with a grounding tab stuck into it might short out the motherboard and prevent the system from booting.

Don't Miss Any Holes or Standoffs (Really)

Check one more time to make sure that there's a brass standoff installed for each mounting hole, and that no brass standoff is installed where there is no mounting hole. One of our technical reviewers suggests installing white nylon standoffs, trimmed to length, in all unused standoff positions covered by the motherboard, particularly those near the expansion slots. Another uses a set of wooden chopsticks. Doing so provides more support to the motherboard, making it less likely that you'll crack the motherboard when you are seating a recalcitrant expansion card.

Figure 4-18. Slide the motherboard into position

Before you secure the motherboard, verify that the back-panel I/O connectors mate properly with the I/O template, as shown in Figure 4-19. The I/O template has metal tabs that ground the back-panel I/O connectors. Make sure that none of these tabs intrude into a port connector. An errant tab at best blocks the port, rendering it unusable, and at worst might short out the motherboard.

After you position the motherboard and verify that the back-panel I/O connectors mate cleanly with the I/O template, insert a screw through one mounting hole into the corresponding standoff, as shown in Figure 4-20.

Figure 4-19. Verify that the back panel connectors mate cleanly with the I/O template

You may need to apply pressure to keep the motherboard positioned properly until you have inserted two or three screws.

If you have trouble getting all the holes and standoffs aligned, insert two screws at opposite corners but don't tighten them completely. Use one hand to press the motherboard into alignment, with all holes matching the standoffs. Then insert one or two more screws and tighten them completely. Finish mounting the motherboard by inserting screws into all standoffs and tightening them.

Figure 4-20. Install screws in all mounting holes to secure the motherboard

4.4.4. Connecting front-panel switch and indicator cables

Once the motherboard is secured, the next step is to connect the front-panel switch and indicator cables to the motherboard. Before you begin connecting front-panel cables, examine the cables. Each connector should be labeled descriptivelyfor example, "Power," "Reset," and "HDD LED." (If not, you'll have to trace each wire back to the front of the case to determine which switch or indicator it connects to.) Match those descriptions with the front-panel connector pins on the motherboard to make sure you connect the correct cable to the appropriate pins. Figure 4-21 shows typical pinouts for the Power Switch, Reset Switch, Power LED, and Hard Drive Activity LED connectors.

Dealing with Misalignment

With top-quality motherboards and cases, all the holes line up perfectly. With cheap products, that's not always true. At times, we've been forced to use only a few screws to secure the motherboard. We prefer to use all of them, both to physically support the motherboard and to make sure all of the grounding points are in fact grounded, but if you simply can't get all of the holes lined up, just install as many screws as you can.

Figure 4-21. Typical front panel connector pinouts (image courtesy of Intel Corporation)


These sample pinouts are for a specific motherboard: the Intel D865PERL. Your motherboard might use different pinouts, so make sure to verify the correct pinouts before you connect the cables.

  • The Power Switch and Reset Switch connectors are not polarized, and can be connected in either orientation.

  • The Hard Drive Activity LED is polarized, and should be connected with the ground (usually black) wire on Pin 3 and the signal (usually red or white) wire on Pin 1.

  • Many motherboards provide two Power LED connectors, one that accepts a 2-position Power LED cable and another that accepts a 3-position Power LED cable with wires in positions 1 and 3. Use whichever is appropriate. The Power LED connectors are usually dualpolarized, and can support a single-color (usually green) Power LED or a dual-color (usually green/yellow) LED.


Although Intel has defined a standard front-panel connector block and uses that standard for its own motherboards, few other motherboard makers adhere to that standard. Accordingly, rather than provide an Intel-standard monolithic connector block that would be useless for motherboards that do not follow the Intel standard, most case makers provide individual 1-, 2-, or 3-pin connectors for each switch and indicator.

Once you determine the proper orientation for each cable, connect the Power Switch, Reset Switch, Power LED, and Hard Drive Activity LED, as shown in Figure 4-22. Not all cases have cables for every connector on the motherboard, and not all motherboards have connectors for all cables provided by the case. For example, the case might provide a speaker cable, but the motherboard might have a built-in speaker and no connection for an external speaker. Conversely, the motherboard might provide connectors for features, such as a Chassis Intrusion Connector, for which no corresponding cable exists on the case; those connectors go unused.

Figure 4-22. Connect the front-panel switch and indicator cables

Three into Two Won't Go

Sometimes you'll encounter a situation where a 2-wire cable has a 3-pin connector, with the wires connected to pins 1 and 3. If the motherboard has a similar connector, there's no problem, but sometimes that cable needs to connect to a motherboard connector with two adjacent pins. Some motherboards provide an alternative 3-pin connector, but many do not. In that case, the best solution is to use a sharp knife or shears to cut the 3-pin connector in half, leaving you with two wires with individual connectors.

When you're connecting front-panel cables, try to get it right the first time, but don't worry too much about getting it wrong. Other than the power switch cable, which must be connected properly for the system to start, none of the other front-panel switch and indicator cables is essential, and connecting them wrong won't damage the system. Switch cablespower and resetare not polarized. You can connect them in either orientation, without worrying about which pin is signal and which ground. If you connect an LED cable backwards, the worst that happens is that the LED won't light. Most cases use a common wire color, usually black, for ground, and a colored wire for signal.

4.4.5. Connecting front-panel ports

Most cases provide one or two frontpanel USB 2.0 ports, and most motherboards provide corresponding internal USB connectors. To route USB to the front panel, you must connect a cable from each frontpanel USB port to the corresponding internal connector. Figure 4-23 shows the standard Intel pinouts for the internal front-panel USB connectors, which are also used by most other motherboard makers.

Figure 4-23. Typical front-panel USB connector pinouts (image courtesy of Intel Corporation)

Some cases provide a monolithic 10-pin USB connector that mates to motherboard USB header pins that use the standard Intel layout. With such a case, connecting the front-panel USB ports is a simple matter of plugging that monolithic connector into the header pins on the motherboard. Unfortunately, some cases instead provide eight individual wires, each with a single connector. Figure 4-24 shows Robert (finally) getting all eight individual wires connected to the proper pins.

Figure 4-24. Connect the front-panel USB cables

Manual Dexterity

Yes, we know it looks as though Robert is sliding a single 4-pin connector onto the header pins, but trust us, those are four individual wires. Arrghh. The best way Robert found to get all the wires connected properly was to clamp the four wires between his fingers aligned as a single connector and then slide the group of connectors onto the header pins. And the second group of four is much harder to get onto the pins than the first set. Several of our tech reviewers (are we the only ones who didn't think of this?) suggested aligning the individual pins correctly, holding them in your fingers, and using a cable tie snugged down to hold them in placethereby making a monolithic connector block out of the original individual connectors.

If your motherboard and case make provision for front-panel FireWire and/or audio connectors, install them the same way, making sure that the pinouts of the connectors and cables correspond.

What About the Optical Disc Audio Cable?

Years ago, connecting an audio cable from the optical drive to the motherboard audio connector or sound card was an essential step, because systems used the analog audio delivered from the optical drive by that cable. If you didn't connect that cable, you didn't get audio from the drive. All recent optical drives and motherboards support digital audio, which is delivered across the bus rather than via a dedicated audio cable. Few optical drives or motherboards include an analog audio cable nowadays, because one is seldom needed.

To verify the setting for digital audio, which is ordinarily enabled by default, use the Windows 2000/XP Device Manager to display the Device Properties sheet for the optical drive. The "Enable digital CD audio…" checkbox should be marked. If it is not, mark the checkbox to enable digital audio. If the checkbox is grayed out, does not appear, or refuses to stay checked after a reboot, your optical drive and/or your motherboard do not support digital audio. In that case, you'll need to use an MPC analog audio cable to connect the drive to the CD-ROM audio connector on the motherboard or your sound card. Also, some older audio applications do not support digital audio, and so require an analog audio cable to be installed even if the system supports digital audio.

Many modern optical drives provide two audio connectors, a 4-pin MPC analog audio connector and a 2-pin digital audio connector that you can connect to a Sony Philips Digital Interface (SP/DIF) audio connector or a Digital-in audio connector on your motherboard or sound card. We suggest that you install an audio cable only if needed. Otherwise, you can do without.

4.4.6. Reconnect the drive data cables

The next step is to reconnect the drive data cables to the motherboard interfaces, as shown in Figure 4-25 and Figure 4-26. Make sure to connect each data cable to the proper interface. See Chapters 7 and 8 for details.

Neatness Counts

After you connect the drive data cables, don't just leave them flopping around loose. That not only looks amateurish, but can impede air flow and cause overheating. Tuck the cables neatly out of the way, using tape, cable ties, or tiewraps to secure them to the case. If necessary, temporarily disconnect the cables to route them around other cables and obstructions, and reconnect them once you have them positioned properly.

Figure 4-25. Connect the Serial ATA data cable(s) to the motherboard interface(s)

Figure 4-26. Connect the ATA data cable(s) to the motherboard interface(s)

4.4.7. Reconnect the ATX Power Connectors

The next step is to reconnect the power connectors from the power supply to the motherboard. The Main ATX Power Connector is a 20-pin or 24-pin connector, usually located near the right front edge of the motherboard. Locate the corresponding cable coming from the power supply, verify that the cable is aligned properly with the connector, and press the cable firmly until it seats fully, as shown in Figure 4-27. The locking tab on the side of the connector should snap into place over the corresponding nub on the socket.

Please Be Seated

Make absolutely certain that the Main ATX Power Connector seats fully. A partially seated connector may cause subtle problems that are very difficult to troubleshoot.

Figure 4-27. Connect the Main ATX Power Connector


Some power supplies are currently shipping with a combination 20-/24-pin connector, in which the regular 20-pin connector has on one end a couple of locking tabs or sliding grooves. The power supply also has a 4-pin connector very similar to the ATX12V connector with matching tabs or rails that you can snap or slide into the 20-pin connector, thus converting it to a 24-pin connector. I've seen people reject this kind of power supply because they don't understand how it works: either they need a 24-pin power supply and the 4-pin connector is unlatched or they need a 20-pin power supply and the 4-pin connector is latched. In either case, they don't figure out the combination mechanism, and so think the power supply is incompatible with their motherboard.

20-pin Versus 24-pin Motherboards and Power Supplies

Many recent motherboards are designed to accept the newer 24-pin ATX Main Power Connector rather than the original 20-pin version of that connector. If the new motherboard is 20-pin and your power supply is 24-pin, you may be able to connect the 24-pin cable to the 20-pin motherboard, leaving the extra four pins unused. If the motherboard has components too near the connector, the 24-pin cable may not seat. In that case, buy an adapter cable that adapts the 24-pin cable to fit the 20-pin motherboard connector.

Conversely, if the motherboard is 24-pin and your power supply 20-pin, the motherboard may require more current than the 20-pin cable can provide. In that case, the motherboard will have a standard Molex (hard drive) power connector. After you connect the 20-pin ATX Main Power Connector cable to the 24-pin socket on the motherboard, connect one of the Molex hard drive power connectors from the power supply to the auxiliary power connector socket on the motherboard. Failing to do this may cause boot failures or other problems.

Pentium 4 systems require more power to the motherboard than the standard ATX Main Power Connector supplies. Intel developed a supplementary connector, called the ATX12V Connector, that routes additional +12V current directly to the VRM (Voltage Regulator Module) that powers the processor. On most Pentium 4 motherboards, the ATX12V connector is located near the processor socket. The ATX12V connector is keyed. Orient the cable connector properly relative to the motherboard connector, and press the cable connector into place until the plastic tab locks, as shown in Figure 4-28.

Figure 4-28. Connect the ATX12V Power Connector


Failing to connect the ATX12V connector is one of the most common causes of initial boot failures on newly built Pentium 4 systems. If nothing happens the first time you power up the system, chances are it's because you forgot to connect the ATX12V connector.

4.4.8. Reinstalling the video adapter

The next step is to reinstall the video adapter and/or any other expansion cards you removed. To do so, align each adapter with the corresponding motherboard slot. Make sure that any external connectors on the card bracket clear the edges of the slot. Carefully align the card with the slot and use both thumbs to press down firmly until it snaps into the slot, as shown in Figure 4-29.

Please Be Seated II

When a newly built system fails to boot, the most common cause is that the video adapter is not fully seated. Some combinations of adapter, case, and motherboard make it devilishly hard to install the adapter properly. It may seem that the adapter is fully seated. You may even hear it snap into place. That's no guarantee. Always verify that the card contacts have fully penetrated the slot, and that the base of the adapter is parallel to the slot and in full contact with it. Many motherboards have a retaining bracket, visible in Figure 4-29 as two brown tabs to the lower right of the heatsink. This bracket mates with a corresponding notch on the video adapter, snapping into place as the adapter is seated. If you need to remove the adapter later, remember to press those tabs to unlock the retaining bracket before you attempt to pull the card.

Figure 4-29. Align the video adapter and press firmly to seat it

After you are certain that the video adapter is fully seated, secure it by inserting a screw through the bracket into the chassis, as shown in Figure 4-30. If the video card has an externally powered fan or requires an external power connection, make sure to connect a power cable to the video adapter before you move on to another task. Install any other expansion cards in the same manner, making sure to connect any power or data cables they require before you start another step.

Figure 4-30. Secure the video adapter bracket with a screw

4.4.9. Finishing up the installation

At this point, the motherboard upgrade is nearly complete. Take a few minutes to double-check everything. Verify that all of the cables are connected properly and that there's nothing loose inside the case. We usually pick up the system and tilt it gently from side to side and then front to back to make sure there are no loose screws or other items that could cause a short. Use the following checklist:

  • Power supply set to proper input voltage (see Chapter 16)

  • No loose tools or screws (shake the case gently)

  • Heatsink/fan unit properly mounted; CPU fan connected (see Chapter 5)

  • Memory modules full seated and latched (see Chapter 6)

  • Front-panel switch and indicator cables connected properly

  • Front-panel I/O, USB, and other internal cables connected properly

  • Hard drive data cable (see Chapter 7) connected to drive and motherboard

  • Hard drive power cable connected

  • Optical drive data cable (see Chapter 8) connected to drive and motherboard

  • Optical drive power cable connected

  • Optical drive audio cable(s) connected, if applicable

  • Floppy drive data and power cables connected (if applicable)

  • All drives secured to drive bay or chassis, as applicable

  • Expansion cards fully seated and secured to the chassis

  • Main ATX power cable connected

  • ATX12V and/or auxiliary power cables connected (if applicable)

  • Front and rear case fans installed and connected (if applicable)

  • All cables dressed and tucked

Only the Good Die Young

When you turn on the rear power switch, the system will come to life momentarily and then die. That's perfectly normal behavior. When the power supply receives power, it begins to start up. It quickly notices that the motherboard hasn't told it to start, and so it shuts down again. All you need to do is press the frontpanel power switch and the system will start normally.

Once you're certain that all is as it should be, it's time for the smoke test. Leave the cover off for now. Connect the power cable to the wall receptacle and then to the system unit. If your power supply has a separate rocker switch on the back that controls power to the power supply, turn that switch to the "1" or "on" position. Press the main power button on the front of the case, and the system should start up. Check to make sure that the power supply fan, CPU fan, and case fan are spinning. You should also hear the hard drive spin up and the happy beep that tells you the system is starting normally. At that point, everything should be working properly.

Turn off the system, disconnect the power cord, reinstall the access panels, and move the system back to its original location. Reconnect the display, keyboard, mouse, and any other external peripherals, and power the system up.

Saving Windows

When you replace the motherboard, unless the replacement is the same model as the original, the existing Windows XP installation is horribly misconfigured for the new motherboard. Although you can strip the hard drive down to bare metal and reinstall everything from scratch, there is an easier way.

  1. Make sure that the system is configured to boot first from the optical drive.

  2. Boot the Windows XP distribution disc. When you're prompted, press Enter to install Windows. (Do not choose the "R" option for Repair Console.) At the license screen, press F8 to accept the license.

  3. Windows Setup detects the existing Windows installation, and gives you the option to install a fresh copy or repair the existing copy. This time, make sure the existing Windows installation is highlighted and press R to choose the Repair option.

  4. Complete Windows Setup and restart the system. (You will probably have to reactivate Windows.)

  5. Install the video, audio, network, and other drivers for the new motherboard.

For additional information, see the Microsoft Knowledge Base Article 315341, "How to perform an in-place upgrade (reinstallation) of Windows XP" (search the Knowledge Base at

Repairing and Upgrading Your PC
Repairing and Upgrading Your PC
ISBN: 059600866X
EAN: 2147483647
Year: 2006
Pages: 126

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