CALL 0207 516 1077


[ home ] [ services ] [ request a service ] [ faqs ]  [ technical forums ]  [ news ] [ useful links ] [ resources ] [ contact us ] [ about us ]

Troubleshooting a new custom-built PC

Remember that the information given here must be considered a general guide and if you do not feel confident to do it yourself, do give us a call to arrange an appointment with a service engineer. OnCallComputerDoctor.co.uk cannot be held responsible for any problems arising from misapplication of the following instructions.

We will address five basic scenarios in this guide, ranging from a stone dead system to a lack of functionality, such as a modem that won't connect. While these procedures will uncover most assembly errors, there is often no way to isolate a dead component without having other known good parts to swap out. In the world of professional PC troubleshooting and repair, the "Swap 'til you drop" strategy is still the most common troubleshooting technique employed. Swapping components requires no expensive diagnostics software or hardware, and is usually the quickest way to isolate a problem. Another reason to steer clear of specialized diagnostics tools is that they are geared to identifying problems with sub-components that can't be fixed anyway. Finding out exactly which address is bad in the system RAM or in the cache memory of a drive or motherboard is of little use when you'll have to replace the whole assembly anyway.

If you smell a burnt electronics odour at any time, you have a blown component and should not attempt powering up again until it is found and replaced, and the cause of the failure is determined. Just give call  08700 116550 and we can arrange an onsite engineer to visit you. Remember that the information given here must be considered a general guide and if you do not feel confident to do it yourself, do give us a call to arrange an appointment with a service engineer. OnCallComputerDoctor.co.uk cannot be held responsible for any problems arising from misapplication of the following instructions.

Where to start:

Scenario 1 - Stone Dead.

You switch on your new system and there are no signs of life; the power supply fan doesn't turn, there are no sounds, no lights.

  • Power supply - Make sure the power cord is fully inserted into the power supply, that the override switch on the back of the supply (if so equipped) is turned on, that the voltage switch is set correctly. Don't neglect to make sure the wall socket you are plugged into is live by unplugging the computer and plugging in a radio or lamp to check.
  • Motherboard connections - Recheck the motherboard documentation for the proper connection of the leads from the front panel power switch. Don't settle for just looking at the switch connection to the motherboard; remove the lead, check that the terminal block matches the documentation then reconnect it. Undo the main power supply connection to the motherboard (this requires pressing in the clasp as you pull gently on the connector), inspect the connectors for damage, and reconnect.
  • Bad component - Disconnect the power cables and ribbon cables from the drives, one drive at a time, retrying power-up after each drive is disconnected. Without reconnecting the drives, remove each adapter card (leave video for last) one at a time, retrying power-up after each removal.
  • Motherboard components - Remove and reinstall memory DIMMs or RIMMs, inspecting for physical damage. Remove and reinstall the heatsink and CPU, double checking the CPU fan is connected to the proper terminal on the motherboard. Never attempt to power up the system without the heatsink installed.
  • Switch - In extremely rare cases, the power switch on the front panel may be faulty. You can use a continuity checker or Ohm-meter to check the switch, or you can carefully, carefully, take a screwdriver with an insulated handle and momentarily short the two pins where the switch lead connects to the motherboard. Although the switch works on low voltage, you may be startled if and when the machine comes on and rake the screwdriver tip across to motherboard, so don't try this unless you have some experience working with live systems.
  • Remove the motherboard from the case and check for loose screws, extra standoffs, and anything else that could cause a short circuit to the motherboard circuitry. Reinstall the motherboard in the case and reinstall the video adapter, then try powering up.

If you still have no power, than the problem is most likely a defective power supply or defective motherboard.

Scenario 2 - Power comes on - Screen is dead

  • Monitor - Make sure that the monitor is plugged into a good power outlet by switching wall sockets with the power supply cord. If the power cord is not permanently attached to the monitor, make sure that it is fully inserted in the socket on the back of the monitor.
  • Connection - Remove the monitor connector from the video card and inspect that none of the pins in the are bent over. Note that some missing pins in the three row high density connector are normal.
  • Video Card - Remove and reseat the video adapter, making sure that the hold down screw doesn't cause the back end of the adapter to lift partially out of the connector. If the video adapter is populated with removable DIMMs, remove and reinstall these.
  • Defective or conflicting adapter on bus - Remove any other adapters installed, one by one, rechecking power-up after each. Don't forget to unplug the power supply or turn off the power strip or override switch before each removal.
  • Double check the motherboard documentation for overlooked CPU selection switches or jumpers settings. Depending on the motherboard used, CPU selection may be automatic.

If you still have no live screen, the problem is likely defective hardware. Make sure that the case speaker is properly connected to the motherboard as per the motherboard documentation. If you hear a series of beeps, note the number and sequence, as they will pinpoint the defective component. The motherboard documentation or manufacture web site should give the codes. If no beeps sound, the most likely candidates are a dead monitor (easily checked by connecting it to another system), a defective motherboard, or a defective power supply. In some rare instances, you may have a bad CPU, RAM or a bad video adapter, and still not hear any beep codes.

Scenario 3 - Screen comes on - No boot

  • No onscreen messages indicating boot failure.
    1. Enter CMOS Setup by following onscreen instructions (usually by hitting the <DEL> or <F1> key). Select the CMOS option to "Restore Default Settings" or similarly phrased option, save and reboot. Note: If you cannot access Setup, double check that the keyboard and mouse connectors aren't interchanged. If you still can't access setup, disconnect power and remove all adapters except the video and disconnect the drives. If you still can't access Setup when you reconnect power, you have some defective hardware, most likely the motherboard, RAM or CPU. These core components should always be bought from the same source to simplify return issues.
    2. If there are still no messages indicating boot failure, enter CMOS Setup again and make sure the CPU speed setting, the bus lock frequency and the IDE interface speed don't exceed your components ratings.
    3. If the system hangs at "Verifying DMI Data Pool", it is usually a motherboard or IDE device problem. Disconnect your IDE cables from the motherboard and see if you can get as far as a "Drive Failure" or "No Boot Device" message. If not, the motherboard will probably need replacing, though you can try discharging the onboard battery first by using the jumper setting in the motherboard manual for disabling a forgotten password.
  • Missing operating system or no boot device message.
    1. Check that the IDE cables are connected to the drives and motherboard properly by removing and reinstalling them. Make sure that the power connectors to all of the drives are properly installed. Make sure that the Master/Slave jumpers for the drives are installed properly
    2. Tries to boot CD and fails - Strangely enough, some high speed CD drives take so long to get up to speed, that the BIOS (motherboard logic) gives up on them before they get there. If the screen displays a message like "Insert CD and hit any key when ready", eject the CD tray, then push it back in, but wait until you hear the drive spin up before striking a key to continue. It make take a few efforts to get this right if it's going to work.
    3. Check the operating system CD is readable in another system, and don't try using pirated operating system software on home recorded CDs.
    4. Enter CMOS Setup and re-arrange the boot sequence so that the CD-ROM or the IDE channel it is connected to is selected as the first boot device. This shouldn't be necessary, but it will help if a previous attempt to install the operating system failed, but left the hard drive looking bootable to the motherboard.
    5. Simplify the system by removing any additional drives so all you have left are a master hard drive on the primary IDE channel and a master CD on the secondary IDE channel.

Scenario 4 - Boots - Locks up during or immediately after operating system install

  • Unplug the power and remove all adapters except the video adapter. Install the operating system. Next install the motherboard drivers from the CD that shipped with the motherboard, and the video adapter driver from its own CD. If the operating system still won't install, check with your parts vendor or the operating system vendor (Microsoft for all Windows versions) for compatibility issues with your components.
  • Install any other adapters one at a time, reconnect power and reboot, allowing the operating system to deal with them individually.
  • Make sure that you are using the approved cabling for any high performance parts such as Ultra 66 or Ultra 100 hard drives, since communications breakdowns at high speeds are likely to show up under the load of operating system installation.

In some rare cases, operating system installation may fail repeatedly because a borderline component is suffering a heat related failure as the system warms up. This is extremely difficult to troubleshoot without parts to swap out, and if you bring the parts back to the point of purchase, it may be hard to convince the vendor that the problem isn't in your imagination. Go through the steps related to CMOS Setup in Scenario 3, and document all the troubleshooting steps you go through for the vendor. Try reinstalling the operating system several times before concluding that you have a heat related failure.

Scenario 5 - Boots and runs

If your operating system installation goes smoothly, but you have trouble accessing a particular device, the problem is as likely to be software as hardware. Extensive software troubleshooting is outside the scope of this book, but we will mention some of the key points you can check in Windows operating systems.

  • A) Floppy Drive
    1. If the activity light on the front of the floppy drive stays lit all the time, the ribbon cable on the drive or the motherboard is probably backwards.
    2. If the drive is not detected properly by CMOS Setup or recognized by the operating system, either the ribbon cable or power cord are partially or improperly connected, or the drive is bad.
    3. For any problems reading or writing specific floppy disks, either the drive is bad, the disk is bad, or the drive that wrote the disk is incompatible with the drive trying to read it due to head alignment issues.
  • B) Hard Drive
    1. Any message indicating a hard drive read or write failure is a hardware error. Try replacing the ribbon cable, making sure you use the newer 80 conductor type.
    2. Isolate the hard drive on its own IDE channel, moving any other drives to the secondary channel on their own cable or temporarily disconnecting them.
    3. If the hard drive is excessively noisy or makes a continual clunking sound, it has suffered internal damage, and odds are even an expensive data recovery outfit won't be able to help.
    4. If the errors persist, either the drive or IDE controller is bad. If you can disable the motherboard IDE controller in CMOS (both channels), you can try substituting an inexpensive PCI IDE controller before giving up on the motherboard.
  • C) CD or DVD Drive
    1. If the drive has trouble reading a particular disc, try wiping off any fingerprints with a clean flannel shirt. Note re-writeable discs written in CDRs and DVDRs are often unreadable in other drives.
    2. For continual read errors, try all of the steps for hard drive troubleshooting; new IDE cable, isolation, swapping IDE controller.
    3. If you can't play music CDs even though your speakers work with other computer sounds, the thin audio cable from the sound card (or motherboard with integrated sound) to the 4 pin connector on the back of the drive is improperly installed or missing.
    4. If you record music CDs on your PC and they won't play in your stereo, make sure you are using CDR blanks, not CDRW.
    5. If you have a CDR or DVDR and your write sessions often fail, try recording at a lower speed, and make sure you are using media certified for at least the speed you are recording at.
  • Modem
    1. Check that the phone line from the wall goes into the modem jack labelled "line". Plug a regular handset into the modem jack labelled phone. If you don't hear a dial tone, either the modem or the phone line is faulty.
    2. In Windows, go to Control Panel > Modems > Diagnostics > and click on "More Info". If your modem doesn't show up in Windows, power down and try removing all of the other adapters except the video card from the PC before rebooting. If Windows still doesn't find your modem, try it in a different motherboard slot. If Windows still can't find the modem, it is probably defective or incompatible.
    3. If you hear the modem dial but the only thing that happens is after a while the operator picks up, you are probably dialling tone on a pulse system.
    4. If you never get connect speeds over 33K, contact your Internet Service Provider with your modem information.
    5. If you connect between 33K and 53K but have frequent disconnects, you probably have aging or overloaded local phone infrastructure. Try another phone jack in your house in case it is a just a poorly wired outlet.
  • Sound Card
    1. Check Windows Device Manager to see if there are any conflicts and be sure that the sound card drivers are installed. If Windows didn't recognize the sound card, try powering down and removing the other adapters except the video card from the PC before rebooting. If Windows still doesn't find your sound card, try it in a different motherboard slot, and if it can't find the sound card, it is probably defective or incompatible.
    2. Make sure that your speakers are plugged into the correct jack on the sound card, because the little pictures can be deceptively similar. Make sure speakers with an external power source are plugged in, turned on, and that the volume dial isn't off.
    3. If you have been using your PC for a while and then lose all sound, the most common reason is the "mute" box being mysteriously check in one of the innumerable mixer panels that install with sound card software. Happy hunting!
  • Network
    1. If the network adapter doesn't appear in device manager, try powering down and removing the other adapters except the video card from the PC before rebooting. If Windows still doesn't find your network adapter, try it in a different motherboard slot, and if it can't find the adapter, it is probably defective or incompatible.
    2. If the card looks healthy in Device manager but you can't connect to your local network, check all the software protocols and identification settings in Control Panel > Network. For home networks, getting the Workgroup name wrong is the most common error.
    3. If you are sure you have all your software setting right by comparing them line for line with another PC on the network, you have a cabling problem. Almost all small networks are wired for 10/100 BaseT, but the cables are often built incorrectly. 10BaseT and 100BaseTX use four conductors in two pairs in an RJ-45 connector, 1&2 and 3&6. Some other standards use all 8 wires, but the important point in every case is that 3&6 must utilize a color coded pair, something many cable makers still neglect.
  • Video
    1. If the screen seems jumpy, particularly from a distance, it could be the monitor itself. Another possibility is interference from electrical equipment, like an external transformer for speakers or other device resting near the speaker. In office environments, electrical wiring in walls carrying high currents can cause wavy interference.
    2. If you look at the screen out of the corner of your eye and it seems to flash near the edges or bottom, the vertical refresh frequency is probably too low. You can try a lower screen resolution, or changing video modes, if the video card software gives you that option.
    3. If you are missing a primary colour, check the 15 pin video connector to see if any of the pins are bent over.

[ home ]   [ services ]   [ request a service ]   [ faqs ]   [ news ]   [ useful links ]   [ contact us ]   [ about us ]

The Computer Doctor, OnCall Computer Doctor, Network Doctor, Data Recovery Doctor, and Data Recovery Lab are trading names for Data Recovery Lab Ltd registered in England & Wales. Reg. No 06268942. VAT GB919408996. Registered Address: Premier House, 309 Ballards Lane, London N12 8LY. Head Office: 145-157 ST JOHN STREET, LONDON, EC1V 4PY.