How to troubleshoot a computer that won’t power on.
There are many reasons why a computer won't turn on and often very few clues about what might be the problem. The only symptom is usually the simple fact that "nothing works" which isn't much to go on.
Add to this the fact that whatever is wrong could be an expensive part of your PC to replace - like the motherboard or CPU.
Note: All of these "computer won't start" troubleshooting guides apply no matter what Windows operating system you have installed on your hard drive, including Windows 7, Windows Vista, and Windows XP. Steps 1 through 5 even apply to other PC operating systems like Linux.
1. Don't Panic! Your Files are Probably OK
When faced with a computer that won't start most people tend to panic, worried that all the data on their PC is gone forever.
It's true that the most common reason a computer won't start is because a piece of hardware has failed or is causing a problem but that hardware isn't usually a hard drive, the part of your computer that stores all of your files.
In other words, your music, documents, emails, and videos are probably safe - just not accessible at the moment.
So take a deep breath and try to relax. There's a good chance you can figure out exactly why your computer won't start and then get it back up and running.
2. Computer Shows No Sign of Power
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Try these steps if your computer will not turn on and is showing no sign at all of receiving power - no fans running and no lights on the computer case.
Important: You may or may not see a light on the back of your PC depending on the kind of power supply you have and the exact cause of the problem.
Note: Don't worry about the monitor yet. If the computer is not turning on because of a power issue then the monitor certainly can't display anything from the computer. Your monitor light will likely be amber/yellow if your computer has stopped sending information to it.
3. Computer Powers On... and Then Off
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Follow these steps if, when you turn your computer on, it promptly powers back off.
You'll probably hear the fans inside your computer turn on, see the lights on the front of your computer turn on or flash, and then it will all stop. You won't see anything on the monitor and you may or may not hear beeps coming from the computer before it shuts off by itself.
Note: As in the previous scenario, don't worry about the state your monitor is in. You may have a monitor issue as well but it's not possible to troubleshoot it quite yet.
4. Computer Powers On But Nothing Happens
If your computer seems to be receiving power after turning it on but you don't see anything on your monitor, try these troubleshooting steps.
In these situations, the power lights will stay on, you'll likely hear the fans inside your PC running, and you may or may not hear one or more beeps coming from the computer.
This situation is probably the most common in my experience working with computers that won't start. Unfortunately it's also one of the most difficult to troubleshoot.
5. Computer Stops or Continuously Reboots During the POST
The POST on your computer may look like the screenshot to your left or may instead simply show your computer maker's logo.
Important: Don't use this troubleshooting guide if you encounter an issue during the loading of the operating system, which occurs after the Power On Self Test is complete. Troubleshooting Windows related reasons why your computer won't turn on begin with #6 below.
6. Windows Begins to Load But Stops or Reboots on a BSOD
This kind of error is called a STOP error but is more commonly referred to as a Blue Screen of Death or a BSOD. Receiving a BSOD error is a common reason why a computer won't turn on.
Important: Choose this troubleshooting guide even if the BSOD flashes on screen and your PC restarts automatically without giving you time to read what it says.
7. Windows Begins to Load But Stops or Reboots Without an Error
Try these steps when your computer powers on, starts to load Windows, but then freezes, stops, or reboots over and over again without generating any kind of error message.
The stopping, freezing, or reboot loop may happen on the Windows splash screen as shown to the left or even on a black screen, with or without a flashing cursor.
Note: If your computer won't start and you see a blue screen flash or remain on the screen, you're experiencing a Blue Screen of Death and should use troubleshooting guide #6 above.
Important: If you suspect that the Power On Self Test is still going on and that Windows has not yet started to boot, a better troubleshooting guide for why your computer won't turn on might be #5 above. It's a fine line and sometimes hard to tell.
8. Windows Repeatedly Returns to the Advanced Boot Options Screen
Use this guide when nothing but the Advanced Boot Options screen appears every time your restart your computer and none of the Windows startup options work.
In this situation, no matter which Safe Mode option you choose, your computer eventually stops, freezes, or restarts on its own, after which you find yourself right back at the Advanced Boot Options menu.
This is a particularly annoying way in which your computer won't turn on because you're trying to use Window's built-in ways to solve your problem but you're getting nowhere with them.
9. Windows Stops or Reboots On or After the Login Screen
Try this troubleshooting guide when your computer powers on, Windows shows the login screen, but then freezes, stops, or reboots here or anytime after.
The stopping, freezing, or reboot loop may happen on the Windows login screen, as Windows is logging you in (as shown to the left), or any time up to Windows fully loading
10. Computer Doesn't Fully Start Because of an Error Message
If your computer turns on but then stops or freezes at any point, showing an error message of any kind, then use this troubleshooting guide.
Error messages are possible at any stage during your computer's boot process, including during the POST, at any time during the loading of Windows, all the way up to the Windows desktop appearing.
Note: The only exception to using this troubleshooting guide for an error message is if the error is a Blue Screen of Death. See #6 above for a better troubleshooting guide for BSOD issues.