PC Troubleshooting Plus

Start with a basic PC set up to eliminate the suspects and find a faulty component

You've just built your PC you're ready to go. You hopefully hit the power button and await the boot up 'bleep' followed by a pleasing flow of text appearing on your monitor - but wait... no bleep, no display, no sounds or lights - what's going on?

Judging by our messaging forums, this is a common horror for our budding PC builders. Having answered many questions on the subject, we've put together this 'advanced troubleshooter' to help you through these difficult times.

With so many complex parts and connections the possibilities of locating the fault seem endless. The reality is that by a simple process of elimination it should be relatively simple (if perhaps a little time consuming) to track down that 'spanner in the works'.

First of all, it is necessary to understand what is happening during the 'boot' process and the minimum hardware needed to achieve a successful boot of the system.

  1. The Power button is pressed
  2. The Motherboard checks that the CPU is able to process information correctly
  3. Built in software called the BIOS is processed by the CPU
  4. The CPU, RAM and Video Card are all checked for basic functionality
  5. The system will give one 'bleep' to indicate that the system passed all the initial tests, or a series of bleeps to indicate a specific fault
  6. The next part of the BIOS is run and a display is sent to the monitor
  7. The BIOS will then do several further tests on connected hardware (RAM, Keyboard, Mouse etc.) and display any errors
  8. The system will then attempt to load the Operating System software from the designated boot drive

From the above procedure we can determine that a 'bootable' system will only need a PSU, Motherboard, CPU, RAM and a Video card. This will be the start point for tracking down the fault...

Back to basics

Assuming that your new PC is completely assembled, you'll need to undo some of your previous work. First off, power the system off and disconnect all the external cables, including the mains cable.

Inside the case, disconnect any IDE and FDD data cables from the motherboard and disconnect all the front panel connectors except the Power switch cable (it is a good idea at this point to double check with the manual that the Power switch cable is connected correctly.)

Also, remove any or all of the adapter cards (e.g. modems, sound cards etc.) except for the video card.

First test boot

Connect just the base unit mains cable and the monitor cable. The rest can be left unconnected for the moment. If there is a switch on the PSU next to where the mains cable plugs in, make sure it is switched to ON.

Press the Power button on the front panel. If your system boots and displays text on the screen, skip to the Bootup is OK, what now? section of this article.

If your system is still not booting at this point, you've eliminated a good deal of possible problems and have only a few parts to test for the fault. We've established that the fault lies either in the PSU, Motherboard, CPU, RAM or Video Card.

Take each part in turn (leaving the motherboard till last) and either replace it with a 'known good' item (i.e. from a working PC) or test it in another working PC. The faulty item can then be easily identified as the one which:

1. When replaced with a 'known good' one allows the PC to boot
2. Causes a good PC to stop working correctly.

If you get as far as testing the Motherboard, it is the item with the problem. Before you take it back for a replacement, there are a couple of things you can do to make sure it is faulty.

1. Double check that your CPU and Memory are compatible with your motherboard and that you have configured the motherboard correctly as per the manual.

2. Locate and follow the procedure in the manual to reset the BIOS.

If you've done all this and still no joy, re-package the motherboard and take/send it back to the retailer for testing/replacement.

Bootup is OK, what now?

If your system booted successfully in the 'Back to basics' section, you will have tested the fundamental parts of your PC. The fault therefore must lay in one the devices presently unconnected in your system.

Fault diagnosis at this stage is easier, but can take longer. Your aim now is to connect one item or connector at a time, then power up the system, then connect another item or connector, power up etc. until the system fails to boot again. One of two things will happen:

1. Once all the items are reconnected the system continues to work correctly (Problem solved!)


2. One of the connections/items will cause the system to fail at the next boot.

If you get to stage 2, the last item you connected has the fault. Confirm that you have connected it correctly, with its instructions (if any) and return it to the retailer if the problem persists.