Have you ever been in a situation where you press the power button on your computer and nothing happens? Or in a position when the computer turns on but fails to boot? If yes, you should probably know how frustrating this situation is.
There are numerous reasons why a computer won't turn on or fail to boot and often very few hints are about what might be the problem.
Today I’d like to walk you into the process of diagnosing a defective computer that won’t turn on or fails to boot. The following guides apply to all computers. In other words, they'll help if your desktop or laptop shows no signs of power or fails to boot. Also, all are applicable no matter what Windows operating system you have installed on your hard drive, including Windows 10, 8, 7, Vista, and Windows XP.
As mentioned, there are many reasons why a computer won't turn on or fail to boot, so, i will divide the troubleshooting process in two cases and explain the main reasons why a computer it's not working properly and how to fix it. Hopefully, any of them helps you if you find yourself in such a situation.
Fist things first: Should you panic about losing your files?
The answer is no! Most people panic when faced with a defective computer that won't start. They are worried that all their valuable data is gone permanently. It's true that the most common reason a computer won't start is because a part of hardware has failed or is causing a problem, but that hardware isn't normally 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, they're just not available at the moment. There's a good chance you can figure out precisely why your computer won't start and then get it back up and running.
Case 1: Computer shows no sign of power when pressing the power button
There are many possible reasons why a desktop, laptop, or tablet computer might not power on. The number one cause why a computer won't turn on is that the power supply cable wasn't plugged in. So before starting a troubleshooting process, make sure you've turned on each power switch and power button included in your computer.
Step 1. First, make a lamp test to verify power is being provided from the charger.
- Your computer isn't going to turn on if it's not getting power, so you need to make sure that the power source is working well.
Step 2. Verify that the power supply voltage switchis set rightly if you're on a desktop computer.
- If the input voltage for the power supply unit (PSU) does not match the exact setting for your country, your computer may not power on at all. For laptops, remove the main battery in the laptop and try using AC power only. If your laptop turns on after trying this, it means that your battery is the reason for the problem and you should replace it.
Step 3. Replace the computer's power cable or AC adapter.
- On a desktop computer, this is the power cable that runs between the computer case and the power source. The AC adapter for a laptop is the cable that you plug into the wall to charge your battery. A bad power cable or AC adapter is a common reason why desktops and laptops won't turn on at all. If you are using a desktop, a bad power cable is a common cause of a computer not receiving power and is very easy to test for. You can use the one that's powering your monitor to test if the problem is at the power cable.
Step 4. Replace the CMOS battery.
- If your computer is more than a few years old or has spent a lot of time turned off or with the main battery removed. A bad CMOS battery is a relatively common cause of a computer that looks like it's not receiving power.
Step 5. Make sure the power switch is attached to the motherboard if you're using a desktop computer.
- This is not a very usual point of failure, but your computer might not be turning on because the power button isn't properly connected to the motherboard. Most case switches are connected to the motherboard via a red and black twisted pair of wires. If these wires aren't securely connected or aren't connected at all, this is probably the problem of your computer not turning on.
Step 6. Test your power supply if you're using a desktop computer.
- At this point in your troubleshooting, it's very possible that the power supply unit in your computer is no longer working and should be replaced. You should, however, test it just to be sure. There's no reason to replace a working piece of hardware when testing it is fairly easy.
Step 7. If you are using a desktop, test the power button on the front of your computer's case and replace it if it fails your testing. Depending on how your computer's case is designed, you may be able to use the reset button in the meantime to power on your computer.
Step 8. Replace your motherboard if you're using a desktop.
- If you're confident that your wall power source, power supply, and power button are working, it's likely that there is a problem with your computer's motherboard and it should be replaced. Be sure you've consumed all of the previous troubleshooting steps that I've given above before replacing your motherboard.
Case 2: Computer reboots itself over and over again without showing anything in the monitor
Is your computer turning off by itself immediately before the operating system loads? If so, you may be encountering anything from an electrical short to a serious hardware issue. Be sure to think about changes you’ve made recently like install a new hardware driver, connect a new hardware component to your computer, or open your computer’s case and do something? It’s possible the hardware driver is buggy or the new hardware is incompatible, or that you accidentally unplugged something while working inside your computer.
Because there are several causes that your computer might be shutting off by itself during the boot process, it's essential that you step through the troubleshooting process that I've described below.
Step 1. Are you hearing a beep code when the computer turns on?
- A beep code will give you a very good idea of exactly where to look for the cause of your computer turning off. Beep codes are especially helpful if the root cause of the problem has something to do with a video. If you can't read an error message or error code on the screen because of a video-related problem, it's definitely going to deter your efforts of finding out what's wrong. This is why having the option to hear the errors as a beep code is so incredibly helpful.
If your computer isn't starting up but is making beeping noises, the first thing you should do is reference your computer or motherboard manual for help translating the beep codes into something meaningful, like a specific issue that's occurring.
While there aren't too many BIOS manufacturers out there, each one does have their own set of beep codes. They might use different patterns and beep lengths - some are really short, some are long, and everywhere in between. So, the same beep sound on two different computers is probably expressing two entirely different problems.
Step 2. Verify that the power supply voltage switch is set correctly.
- If the input voltage for the power supply does not match the correct setting for your country, your computer may not stay powered on. Chances are your computer wouldn't power on at all if this switch is wrong, but an incorrect power supply voltage might also cause your computer to turn off by itself.
Step 3. Test your power supply.
- Just because your computer came on for a few moments doesn't mean that the power supply unit in your computer is working properly. In my experience, the power supply tends to cause more problems than any other piece of hardware and is very often the cause of a computer turning off by itself.
Step 4. Reseat hardware components inside of your computer.
- Before touching the internal components of your computer, make sure that you have disconnected the power cable and also discharged remaining electricity by pressing and holding the power button while the computer is disconnected. Reseating Internal Data, Power Cables, Expansion Cards and Memory Modules will reestablish all of the connections inside your computer which may have wiggled loose over time.
Step 5. Clear CMOS (Reset BIOS)
- Clearing the CMOS on your motherboard will reset your BIOS settings to their factory defaults, the settings that the motherboard maker decided were the ones that most people would use.
One reason to clear CMOS is to help troubleshoot or solve certain computer problems or hardware compatibility issues. Many times, a simple BIOS reset is all you need to get a seemingly dead computer back up and running. After clearing the CMOS you may need to access the BIOS setup utility and reconfigure some of your hardware settings.
Below i will provide two different ways to clear CMOS. These methods are related to the problem when monitor doesn't show anything and computer reboot's itself over and over again.
Method one: Clear CMOS by reseating the CMOS battery
- By disconnecting and then reconnecting the CMOS battery, you remove the source of power that saves your computer's BIOS settings, resetting them to default. The CMOS battery in most desktop computers is much easier to find and looks just like a standard cell-type battery like you'd find in small toys or traditional watches. Clearing CMOS, in this case, involves popping the battery out and then putting it back in.
Method two: Clear CMOS using BIOS jumper
- Make sure your computer is unplugged and then open it up. Look around your motherboard's surface for a jumper (as shown in the picture) with the CLEAR CMOS label, which will be located on the motherboard and near the jumper.
Move the little plastic jumper from the 2 pins it's on over to the other pins (in a 3-pin setup where the center pin is shared) or remove the jumper entirely if this is a 2-pin setup. Any confusion here can be cleared up by checking the CMOS clearing steps outlined in your computer or motherboard manual.
Turn the computer back on and make sure that the BIOS settings have reset, or the system password is now cleared–if that's why you were clearing CMOS.
If everything is normal, turn off your computer, return the jumper to its original position, and then turn the computer back on. If you don't do this, CMOS will clear on every restart of your computer!
Step 6. Replace each essential hardware in your computer with an identical or equivalent spare piece of hardware, one component at a time, to determine which piece of hardware is causing your computer to shut off automatically. Test after each hardware replacement to determine which device is faulty.
Finally, if all of these steps fail to fix your problem, you'll likely need to seek professional help from a computer repair service or from your computer manufacturer's technical support.