Introduction: In this article, we will teach you what you should do if your computer doesn’t turn on.By “computer doesn’t turn on” we mean that your computer is “dead,” i.e., nothing shows up on its screen. If you can see something on the screen, your computer is turning on, and thus we won’t cover what is happening with your computer in this tutorial. (If this is your case, you have a different problem: your computer isn’t loading the operating system – i.e., isn’t booting. The main reason for this sort of situation is that users start trying several different things without a standardized procedure, and by the end of the day, they don’t remember what they have already tried. Worse than that, many assume that they understand how computers work, which is usually not the case. A good example is users saying that the motherboard is good and it is “trying to boot” because they can hear the hard disk drive spinning.

The following components are needed to turn on the computer:

  • Power supply
  • Motherboard
  • CPU
  • CPU cooler
  • One memory module
  • One video card

Everything else that you might have must be removed from your computer. This includes all add-on cards you may have (e.g., add-on sound card), hard disk drives, optical disk drives, memory modules (leave just one installed), your second video card, case fans, extra fans, etc. If your motherboard has on-board video and you have an add-on video card installed, remove the video card and install the video monitor cable on the on-board video connector.

If your computer is still not turning on, it means that one of the parts listed above is defective, or you have a bad contact problem. Before we continue, take a good look at what happens when you try to turn on your computer, this time with the case opened and with only the parts listed above installed:

  • Is the power supply delivering energy? You can check this by seeing if the LEDs present on the motherboard and/or the green LED present on the case frontal panel are turning on when you press the case on/off switch. If it isn’t delivering energy, this means that the power supply is defective and must be replaced.
  • Is the CPU fan spinning? If it isn’t, and assuming that the power supply isn’t defective, the CPU fan is defective and must be replaced. Several motherboards have a protection circuit that will shut down the system if the CPU fan is defective.
  • Does the computer seem to be working for some seconds and then it shuts down (i.e., the CPU fan spins for some seconds, and then the PC turns off by itself)? This can be several things, but for now you should try resetting the CMOS memory. (We will describe this procedure in the next page.)
  • Can you hear any beeps coming from the small speaker located in the case? If you can, this means that you probably have a bad contact problem on your video card or memory modules (more about this later) or they are defective.