How to Troubleshoot an HP Computer That Is Not Booting

By J.E. Myers

It's no secret that computers are complex hives of many dependent pieces of hardware. When something goes wrong and the computer won't boot, it isn't always obvious what part of the computer has failed. Troubleshooting "failure to boot" in an HP desktop computer---or any desktop computer for that matter---is a painstaking, step-by-step process of elimination in most cases. But if you follow a logical protocol of testing, you should find the root of the problem eventually.

Things You'll Need

  • Helpful: power supply tester
  • Optional: new power supply
  • USB external hard drive enclosure
  • Second "known good" computer
  • Phillips head screwdriver

Step 1

Check the power source. It may sound ridiculous but making sure the computer is plugged into a viable power outlet is a smart "first step." Wall outlets can short out, power cords can be unplugged by accident, power strips and surge protectors do fail or get switched off. Verify that the power is getting from the wall outlet to the back of the computer.

Step 2

Test the power supply. Unplug all the cables to the back of the computer. Open the side cover. Disconnect the power supply from the motherboard and from the hard drive. Use a power supply tester or purchase a similar power supply box (matching the pin types and the output in watts) from a computer parts dealer. If the tester shows any red lights the power supply box is dead. If you connect a known-good power supply to the motherboard and the hard drive, and start the computer, and it boots, your old power supply failed. If it doesn't boot, remove the power supply or continue to use it: A fresh power supply is never a bad idea.

Step 3

Examine the motherboard. When the power cord is plugged in you should see a green or amber LED light illuminated on the motherboard. If you see the LED bulb, but it is not glowing, your motherboard could be damaged. Unplug all the cables from the back of the computer. Find the nickel-sized "clock battery" on the board and remove it. Press the power button to discharge any latent electricity in the board. Replace the battery and try to start the computer again. If it boots now, this means your motherboard encountered a problem and turned itself off. Consider replacing it before it fails again.

Step 4

Remove all of the add-in PCI cards that may be present. Plug your monitor into the onboard video port instead of the PCI video card if you had one and removed it. Reboot. If the computer boots now, one of the PCI cards has a problem or a driver is missing. Start adding back the PCI cards, one at a time, until you find the card that causes the computer not to boot anymore. Replace this faulty PCI card.

Step 5

Disconnect the hard drive from the case and insert it in an external hard drive enclosure with a USB connection. Plug the hard drive into a working computer and see if the hard drive can be "read" by the computer. Go to "My Computer" and look for the external hard drive. If you can't find this drive, chances are the hard drive is damaged. Replace it with a new drive and reinstall Windows.

Step 6

Repair or reinstall Windows if the machine otherwise starts up but then fails or "blue screens" just before, or just after, the Window start up screen appears on the monitor. This is usually the sign of a corrupt Windows component, errors on the hard drive where Windows resides, or of a serious "fake alert" virus.

Tips & Warnings

  • HP laptops that won't boot offer fewer testing options for the DIYer unfortunately. Other than checking the AC Adapter brick, removing the battery, examining the AC power-in port for a loose connector pin, and/or replacing the hard drive, there are few in-depth tests an amateur can conduct to solve a boot failure. Contact HP Support or take your laptop to a professional repair depot for further help diagnosing a boot failure.