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Building the Perfect PC by Barbara Fritchman Thompson, Robert Bruce Thompson

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Many first-time system builders are haunted by the question, “What if it doesn’t work?” Or, worse still, “What if it goes up in flames the first time I turn it on?” Set your mind at ease. This isn’t rocket surgery. Any reasonably intelligent person can build a system with a high degree of confidence that it will work normally the first time it is turned on. If you use good components and assemble them carefully, you’re actually less likely to encounter problems with a home-built system than with a prebuilt mail-order system or with a system off the shelf from your local superstore.


Shipping can be tough on a computer. We always pop the cover of PCs that have been shipped, and often find that something has been jarred loose. Our editor reports that when he shipped a PC to his parents, it arrived with the AGP card completely out of its slot. Not good.

Even worse, shipping can cause the CPU cooler to break loose, particularly on AMD Athlon XP systems. A heavy heatsink rattling around can do some serious damage to other components, but even that’s not the major concern. Running a system without a CPU cooler causes an Athlon XP to go up in smoke in seconds, literally. If someone ships a system to you, always open it up and verify that everything is properly connected before you apply power to the system.

Still, problems can happen. So, while it would take a whole book to cover troubleshooting in detail, it’s worth taking a few pages to list some of the most likely problems and solutions. Fortunately, it’s easier to troubleshoot a newly built system than a system that’s been in use for some time. Fewer things can go wrong with a new system. You can be certain that the system is not infected with a virus or malware, for example, and driver problems are much less likely on a new system because you have all the latest drivers installed.

The best time to troubleshoot is while you’re building the system. A good carpenter measures twice and cuts once. Take the same approach to building your system, and you’re unlikely to need any of this troubleshooting advice. As you build the system, and then again before you apply power for the first time, verify that all cables are oriented and connected correctly. Make sure expansion cards, memory modules, the processor, and so on are fully seated, and that you haven’t left a tool in the patient. Each project system chapter includes a final checklist. Verifying the items on that checklist eliminates about 99% of potential problems.

Possible problems fall into one of four categories: easy versus hard to troubleshoot, and likely versus unlikely. Always check the easy/likely problems first. Otherwise, you may find yourself replacing the video card before you notice that the monitor isn’t plugged in. After you exhaust the easy/likely possibilities, check the easy/unlikely ones, followed by hard/likely, and, finally, hard/unlikely.

Other than sheer carelessness—to which experienced system builders are more prone than are novices—most problems with new systems result from one or more of the following:

  • Cable problems. Disconnected, mis-connected, and defective cables cause more problems than anything else. The plethora of cables inside a PC makes it very easy to overlook a disconnected data cable or to forget to connect power to a drive. It’s possible to connect some cables backward. Ribbon cables are a particularly common problem because some can be connected offset by a row or column of pins. And the cables themselves cannot always be trusted, even if they are new. If you have a problem that seems inexplicable, always suspect a cable problem first.


    Fortunately, most problems with defective cables involve ribbon cables, and those are pretty easy to come by. For example, when we recently assembled a new PC, the motherboard came with two IDE cables and a floppy drive cable. The floppy drive came with a cable, the hard drive with another IDE cable, and the optical drive with still another IDE cable. That gave us four IDE cables and two floppy cables, so we ended up with two spare IDE cables and a spare floppy cable. Those went into our spares kit, where they’ll be available if we need to swap cables to troubleshoot another system.

    One of our technical reviewers observes: “A good flashlight with a tight beam (I use a mini Maglight) really helps to spot offset ribbon connector problems, even if workspace lighting is otherwise adequate. I’ve done systems where a handheld magnifier became an indispensable tool.”

  • Configuration errors. Years ago, motherboards required a lot more manual configuration than modern motherboards do. There were many switches and jumpers, all of which had to be set correctly or the system wouldn’t boot. Modern motherboards auto-configure most of their required settings, but may still require some manual configuration, either by setting physical jumpers on the motherboard or by changing settings in CMOS Setup.


    Motherboards use silk-screened labels near jumpers and connectors to document their purposes and to list valid configuration settings. These settings are also listed in the motherboard manual. Although it is rare, we have encountered errors in the silk-screened motherboard labels or the manuals. (On one notable occasion, the motherboard labels and the manual agreed and were both wrong, which cost us several hours of aggravation.) Always check both the motherboard labels and the manual to verify configuration settings. If the motherboard maker posts updated manuals on the Web, check those as well.

  • Incompatible components. In general, you can mix and match modern PC components without worrying much about compatibility. For example, any hard drive or optical drive works with any IDE interface, and any ATX12V power supply is compatible with any ATX12V motherboard (although the power supply may not have adequate power). Most component compatibility issues are subtle. For example, you may install a 1 GB memory module in your new system, but when you power it up, the system sees only 256 MB or 512 MB because the motherboard doesn’t recognize 1 GB memory modules properly. All of the components we recommend in the project system chapters are compatible with one another, but if you use other components it’s worth checking the detailed documentation on the manufacturers’ web sites to verify compatibility.

  • Dead-on-arrival components. Modern PC components are extremely reliable, but if you’re unlucky one of your components may be DOA. This is the least likely cause of a problem, however. Many first-time system builders think they have a DOA component, but the true cause is almost always something else—usually a cable or configuration problem. Before you return a suspect component, go through the detailed troubleshooting steps we describe. Chances are the component is just fine.


A healthy PC finishes the POST (Power-On Self-Test) with one happy-sounding beep. If you hear some other beep sequence during startup, there is some sort of problem. BIOS beep codes provide useful troubleshooting information, such as identifying the particular subsystem affected. Beep codes vary, so check the motherboard documentation for a description of what each code indicates.

Here are the problems you are most likely to encounter with a new system, and what to do about them.

Problem: When you apply power, nothing happens.

  1. Verify that the power cable is connected to the PC and to the wall receptacle, and that the wall receptacle has power. Don’t assume. We have seen receptacles in which one half worked and the other didn’t. Use a lamp or other appliance to verify that the receptacle to which you connect the PC actually has power. If the power supply has its own power switch, make sure that the switch is turned to the “On” or “1” position. If your local mains voltage is 110/115/120V, verify that the power supply voltage selector switch, if present, is not set for 220/230/240V. (If you need to move this switch, disconnect power before doing so.)

  2. If you are using an outlet strip or UPS, make sure that its switch (if it has one) is on and that the circuit breaker or fuse hasn’t blown.

  3. If you installed an AGP video adapter, pop the lid and verify that the AGP adapter is fully seated in its slot. Even if you were sure that it seated fully initially—and even if you thought it snapped into place—the AGP adapter still may not be properly seated. Remove the AGP card and reinstall it, making sure it seats completely. If the motherboard has an AGP retention mechanism, make sure the notch on the AGP card fully engages the mechanism. Ironically, one of the most common reasons for a loose AGP card is that the screw used to secure it to the chassis may torque the card, pulling it partially out of its slot. This problem is rare with high-quality cases and AGP cards, but quite common with cheap components.

  4. Verify that the main ATX power cable and the ATX12V power cable are securely connected to the motherboard and that all pins are making contact. If necessary, remove the cables and reconnect them. Make sure the latch on each cable plug snaps into place on the motherboard jack.

  5. Verify that the front-panel power switch cable is connected properly to the front-panel connector block. Check the silkscreen label on the motherboard and the motherboard manual to verify that you are connecting the cable to the right set of pins. Very rarely, you may encounter a defective power switch. You can eliminate this possibility by temporarily connecting the front-panel reset switch cable to the power switch pins on the front-panel connector block. (Both are merely momentary on switches, so they can be used interchangeably.) Alternatively, you can carefully use a small flat-blade screwdriver to short the power switch pins on the front-panel connector block momentarily. If the system starts with either of these methods, the problem is the power switch.

  6. Start eliminating less likely possibilities, the most common of which is a well-concealed short circuit. Begin by disconnecting the power and data cables from the hard, optical, and floppy drives, one at a time. After you disconnect each one, try starting the system. If the system starts, the drive you just disconnected is the problem. The drive itself may be defective, but it’s far more likely that the cable is defective or was improperly connected. Replace the data cable and connect the drive to a different power supply cable.


    If you have a spare power supply—or can borrow one temporarily from another system—you might as well try it as long as you have the cables disconnected. A new power supply being DOA is fairly rare, at least among good brands, but if you have the original disconnected it’s not much trouble to try a different one.

  7. If you have expansion cards installed, remove them one by one, except for the AGP adapter. If the motherboard has embedded video, temporarily connect your display to it and remove the AGP card as well. Attempt to start the system after you remove each card. If the system starts, the card you just removed is causing the problem. Try a different card or install that card in a different slot.

  8. Remove and reseat the memory modules, examining them to make sure they are not damaged, and then try to start the system. If you have two memory modules installed, install only one of them initially. Try it in both (or all) memory slots. If the module doesn’t work in any slot, it may be defective. Try the other module, again in every available memory slot. By using this approach, you can determine if one of the memory modules or one of the slots is defective.

  9. Remove the CPU cooler and the CPU. Check the CPU to make sure there are no bent pins. If there are, you may be able to straighten them using a credit card or a similar thin, stiff object, but in all likelihood you will have to replace the CPU. Check the CPU socket to make sure there are no blocked holes or foreign objects present.


    Before you reinstall the CPU, always remove the old thermal compound and apply new compound. You can generally wipe off the old compound with a paper towel, or perhaps by rubbing it gently with your thumb. (Keep the processor in its socket while you remove the compound.) If the compound is difficult to remove, try heating it gently with a hair dryer. Never operate the system without the CPU cooler installed.

  10. Remove the motherboard and verify that no extraneous screws or other conductive objects are shorting the motherboard to the chassis. Although shaking the case usually causes such objects to rattle, a screw or other small object may become wedged so tightly between the motherboard and chassis that it will not reveal itself during a shake test.

  11. If the problem persists, the most likely cause is a defective motherboard.

Problem: The system seems to start normally, but the display remains black.

  1. Verify that the display has power and the video cable is connected. If the display has a non-captive power cable, make sure the power cord is connected both to the display and to the wall receptacle. If you have a spare power cord, use it to connect the display.

  2. Verify that the brightness and contrast controls of the display are set to midrange or higher.

  3. Disconnect the video cable and examine it closely to make sure that no pins are bent or shorted. Note that the video cable on some monitors is missing some pins and may have a short jumper wire connecting other pins, which is normal. Also check the video port on the PC to make sure that all of the holes are clear and that no foreign objects are present.

  4. If you are using a standalone AGP adapter in a motherboard that has embedded video, make sure the video cable is connected to the proper video port. Try the other video port just to make sure. Most motherboards with embedded video automatically disable it when they sense that an AGP card is installed, but that is not universally true. You may have to connect the display to the embedded video, enter CMOS Setup, and reconfigure the motherboard to use the AGP card.

  5. Try using a different display if you have one available. Alternatively, try using the problem display on a known-good system.

  6. If you are using an AGP card, make certain it is fully seated. Many combinations of AGP card and motherboard make it very difficult to seat the card properly. You may think the card is seated, and may even feel it snap into place. That does not necessarily mean it really is fully seated. Look carefully at the bottom edge of the card and the AGP slot, and make sure the card is fully in the slot and parallel to it. Verify that installing the screw that secures the AGP card to the chassis did not torque the card, forcing one end up and out of the slot.

  7. If the system has PCI expansion cards installed, remove them one by one. (Be sure to disconnect power from the system before you remove or install a card.) Each time you remove a card, restart the system. If the system displays video after you remove a card, that card is either defective or is conflicting with the AGP adapter. Try installing the PCI card in a different slot. If it still causes the video problem, the card is probably defective. Replace it.

Problem: When you connect power (or turn on the main power switch on the back of the power supply), the power supply starts briefly and then shuts off.


All of the following steps assume that the power supply is adequate for the system configuration. This symptom may also occur if you are using a grossly underpowered power supply. Worse still, doing that may damage the power supply itself, the motherboard, and other components.

  1. This may be normal behavior. When you connect power to the power supply, it senses the power and begins its startup routine. Within a fraction of a second, the power supply notices that the motherboard hasn’t ordered it to start, so it shuts itself down immediately. Press the main power switch on the case and the system should start normally.

  2. If pressing the main power switch doesn’t start the system, you have probably forgotten to connect one of the cables from the power supply or front panel to the motherboard. Verify that the power switch cable is connected to the front-panel connector block, and that the 20-pin main ATX power cable and the 4-pin ATX12V power cable are connected to the motherboard. Connect any cables that are not connected and press the main power switch, and the system should start normally.

  3. If the preceding steps don’t solve the problem, the most likely cause is a defective power supply. If you have a spare power supply or can borrow one from another system, install it temporarily in the new system. Alternatively, connect the problem power supply to another system to verify that it is bad.

  4. If none of the preceding steps solves the problem, the most likely cause is a defective motherboard. Replace it.

Problem: When you apply power, the floppy drive LED lights solidly and the system fails to start.

  1. The FDD cable may be misaligned. Verify that the FDD cable is properly installed on the FDD and on the motherboard FDD interface. You may have installed the FDD cable backward or installed it offset by one row or column of pins.

  2. If the FDD cable is properly installed, it may be defective. Disconnect it temporarily and start the system. If the system starts normally, replace the FDD cable.

  3. If the FDD cable is known-good and installed properly, the FDD itself or the motherboard FDD interface may be defective. Replace the FDD. If that doesn’t solve the problem and you insist on having an FDD, either replace the motherboard or disable the motherboard FDD interface and install a PCI adapter that provides an FDD interface.

Problem: The optical drive appears to play audio CDs, but no sound comes from the speakers.

  1. Make sure the volume/mixer is set appropriately, i.e., the volume is up and CD Audio isn’t muted. There may be multiple volume controls in a system. Check them all.

  2. Try a different audio CD. Some recent audio CDs are copy-protected in such a way that they refuse to play on a computer optical drive.

  3. If you have tried several audio CDs without success, this may still be normal behavior, depending on the player application you are using. Optical drives can deliver audio data via the analog audio-out jack on the rear of the drive or as a digital bit stream on the bus. If the player application pulls the digital bit stream from the bus, sound is delivered to your speakers normally. If the player application uses analog audio, you must connect a cable from the analog audio-out jack on the back of the drive to an audio-in connector on the motherboard or sound card.

  4. If you install an audio cable and still have no sound from the speakers, try connecting headphones or amplified speakers directly to the headphone jack on the front of the optical drive (if present). If you still can’t hear the audio, the drive may be defective. If you can hear audio via the front headphone jack but not through the computer speakers, it’s likely the audio cable you installed is defective or installed improperly.

Problem: S-ATA drives are not recognized.

  1. How S-ATA drives are detected (or not detected) depends on the particular combination of chipset, BIOS revision level, S-ATA interface, and the operating system you use. Failing to recognize S-ATA devices may be normal behavior.

  2. If you use a standalone PCI S-ATA adapter card, the system will typically not recognize the connected S-ATA drive(s) during startup. This is normal behavior. You will have to provide an S-ATA device driver when you install the operating system.

  3. If your motherboard uses a recent chipset, e.g., an Intel 865 or later, and has embedded S-ATA interfaces, it should detect S-ATA devices during startup and display them on the BIOS boot screen. If the drive is not recognized, update the BIOS to the latest version if you have not already done so. Restart the system and watch the BIOS boot screen to see if the system recognizes the S-ATA drive. Run BIOS Setup and select the menu item that allows you to configure ATA devices. If your S-ATA drive is not listed, you can still use it, but you’ll have to provide a driver on diskette during OS installation.

  4. Recognition of S-ATA drives during operating system installation varies with the OS version and the chipset. The original release of Windows 2000 does not detect S-ATA drives with any chipset. To install Windows 2000 on an S-ATA drive, watch during the early part of Setup for the prompt to press F6 if you need to install third-party storage drivers. Press F6 when prompted and insert the S-ATA driver floppy. Windows XP may or may not recognize S-ATA drives, depending on the chipset the motherboard uses. With recent chipsets, e.g., the Intel 865 series and later, Windows XP recognizes and uses S-ATA drives natively. With earlier chipsets, e.g., the Intel D845 and earlier, Windows XP does not recognize the S-ATA drive natively, so you will have to press F6 when prompted and provide the S-ATA driver on floppy. Most recent Linux distributions (those based on the 2.4 kernel or later) recognize S-ATA drives natively.

  5. If the S-ATA drive is still not recognized, pop the lid and verify that the S-ATA data and power cables are connected properly. Try removing and reseating the cables and, if necessary, connecting the S-ATA drive to a different motherboard interface connector. If the drive still isn’t accessible, try replacing the S-ATA data cable. If none of this works, the S-ATA drive is probably defective.

Problem: The monitor displays BIOS boot text, but the system doesn’t boot and displays no error message.

  1. This may be normal behavior. Restart the system and enter BIOS Setup (usually by pressing Delete or F1 during startup). Choose the menu option to use default CMOS settings, save the changes, exit, and restart the system.

  2. If the system doesn’t accept keyboard input and you are using a USB keyboard and mouse, temporarily swap in a PS/2 keyboard and mouse. If you are using a PS/2 keyboard and mouse, make sure you haven’t connected the keyboard to the mouse port and vice versa.

  3. If the system still fails to boot, run BIOS Setup again and verify all settings, particularly CPU speed, FSB speed, and memory timings.

  4. If the system hangs with a DMI pool error message, restart the system and run BIOS Setup again. Search the menus for an option to reset the configuration data. Enable that option, save the changes, and restart the system.

  5. If you are using an Intel motherboard, power down the system and reset the configuration jumper from the 1-2 (Normal) position to the 2-3 (Configure) position. Restart the system, and BIOS Setup will appear automatically. Choose the option to use default CMOS settings, save the changes, and power down the system. Move the configuration jumper back to the 1-2 position and restart the system. (Actually, we do this routinely any time we build a system around an Intel motherboard. It may not be absolutely required, but we’ve found that it minimizes problems.)

  6. If you are still unable to access BIOS Setup, power down the system, disconnect all of the drive data cables, and restart the system. If the system displays a Hard Drive Failure or No Boot Device error message, the problem is a defective cable (more likely) or a defective drive. Replace the drive data cable and try again. If the system does not display such an error message, the problem is probably caused by a defective motherboard.

Problem: The monitor displays a Hard Drive Failure or similar error.

  1. This is almost always a hardware problem. Verify that the hard drive data cable is connected properly to the drive and the interface and that the drive power cable is connected.

  2. Use a different drive data cable and connect the drive to a different power cable.

  3. Connect the drive data cable to a different interface.

  4. If none of these steps corrects the problem, the most likely cause is a defective drive.

Problem: The monitor displays a No Boot Device, Missing Operating System, or similar error message.

  1. This is normal behavior if you have not yet installed an operating system. Error messages like this generally mean that the drive is physically installed and accessible, but the PC cannot boot because it cannot locate the operating system. Install the operating system.

  2. If the drive is inaccessible, verify that all data and power cables are connected properly. If it is a parallel ATA drive, verify that the master/slave jumpers are set correctly and that the drive is connected to the primary interface.

Problem: The system refuses to boot from the optical drive.

  1. All modern motherboards and optical drives support the El Torito specification, which allows the system to boot from an optical disc. If your new system refuses to boot from a CD, first verify that the CD is bootable. Most, but not all, operating system distribution CDs are bootable. Some OS CDs are not bootable, but have a utility program to generate boot floppies. Check the documentation to verify that the CD is bootable, or try booting the CD in another system.

  2. Run CMOS Setup and locate the section where you can define boot sequence. The default sequence is often (1) floppy drive, (2) hard drive, and (3) optical drive. Sometimes, by the time the system has decided it can’t boot from the FDD or hard drive, it “gives up” before attempting to boot from the optical drive. Reset the boot sequence to (1) optical drive and (2) hard drive. We generally leave the system with that boot sequence. Most systems configured this way prompt you to “Press any key to boot from CD” or something similar. If you don’t press a key, the system then attempts to boot from the hard drive, so make sure to pay attention during the boot sequence and press a key when prompted.

  3. Some high-speed optical drives take several seconds to load a CD, spin up, and signal the system that they are ready. In the meantime, the BIOS may have given up on the optical drive and gone on to try other boot devices. If you think this has happened, try pressing the reset button to reboot the system while the optical drive is already spinning and up to speed. If you get a persistent prompt to “press any key to boot from CD,” try leaving that prompt up while the optical drive comes up to speed. If that doesn’t work, run CMOS Setup and reconfigure the boot sequence to put the FDD first and the optical drive second. (Make sure there’s no diskette in the FDD.) You can also try putting other boot device options (e.g., a Zip drive, network drive, or boot PROM) ahead of the optical drive in the boot sequence. The goal is to provide sufficient delay for the optical drive to spin up before the motherboard attempts to boot from it.

  4. If none of these steps solves the problem, verify that all data cable and power cable connections are correct, that master/slave jumpers are set correctly, and so on. If the system still fails to boot, replace the optical drive data cable.

  5. If the system still fails to boot, disconnect all drives except the primary hard drive and the optical drive. If they are parallel ATA devices, connect the hard drive as the master device on the primary channel and the optical drive as the master device on the secondary channel, and restart the system.

  6. If that fails to solve the problem, connect both the hard drive and the optical drive to the primary ATA interface, with the hard drive as master and the optical drive as slave.

  7. If the system still fails to boot, the optical drive is probably defective. Try using a different drive.

Problem: When you first apply power, you hear a continuous high-pitched screech or warble.

  1. The most likely cause is either that one of the system fans has a defective bearing, or that a wire is contacting the spinning fan. Examine all the system fans—CPU fan, power supply fan, and any supplemental fans—to make sure they haven’t been fouled by a wire. Sometimes it’s difficult to determine which fan is making the noise. In that case, use a cardboard tube or rolled-up piece of paper as a stethoscope to localize the noise. If the fan is fouled, clear the problem. If the fan is not fouled but still noisy, replace the fan.

  2. Rarely, a new hard drive may have a manufacturing defect or may have been damaged in shipping. If so, the problem is usually obvious from the amount and location of the noise and possibly because the hard drive is vibrating. If necessary, use your cardboard-tube stethoscope to localize the noise. If the hard drive is the source, the only alternative is to replace it.

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