How to Fix a Computer That Fails to Startup

How to Fix a Desktop Computer That Fails to Start Up
1. Check the power source. Go to the wall outlet where the computer, or its power strip, is plugged in and work toward the computer. Fix any problem you find and test your machine again.
2. Disconnect all cables coming out of the back of your desktop. Remove the cover. Reconnect the power cord. When you press the 'On' button, do any tiny lights illuminate on the motherboard, the power supply, or the status indicator lights on the front? If neither lights nor sound are emitted, your power supply may be dead.
3. Shut down the machine. Disconnect the power supply from the motherboard and any drives or other devices. Remove the four screws that hold the power supply in place on the chassis. Remove the power supply box.
4. Use a power supply tester to quickly test the box. If any lights come up red on the tester, the power supply is dead. If you don't have a tester, acquire an identical power supply you know is good from another source, such as another computer, and substitute it for a 'tester.'
5. Rest this 'tester' power supply on the outside of the computer. Plug it into the motherboard. Plug the monitor cable back in. Turn on the computer. If the computer boots to BIOS, your original power supply is certainly bad. Replace it before continuing testing.
6. Shut down the computer. Gently remove the silver clock battery from the motherboard. Press the power button to clear any residual electricity. Now put the clock battery back in. Reconnect the monitor and reboot. If the computer doesn't boot to BIOS, your motherboard is most likely bad. If it passes this test, continue.
7. Test the hard drive last. Shut down the computer. Switch the electrical connector serving the hard drive with a different one. Test again. If that doesn't work, disconnect the IDE cable connecting the hard drive to the motherboard and replace it with another IDE cable. If these steps fail to boot the drive, shut the computer down. Remove the hard drive. Install the hard drive as a proper slave drive on another computer and see if can be read by this other machine. Turn on the computer and go to 'Start,' 'My Computer,' and look for this slave drive. If it can't be found, the hard drive is probably dead. Replace it and reinstall Windows.