Among the many ways a computer won’t turn on, a complete loss of power is rarely the worst case scenario. There is a possibility that the computer is not receiving power due to a serious problem, but it is unlikely.
There are several possible reasons why a desktop, laptop, or tablet might not be on, so it’s very important that you follow a thorough troubleshooting procedure like the one outlined below.
- Difficulty : Medium
- Time Required : Anywhere from minutes to hours, depending on why the computer is not receiving power
- What You’ll Need : Your AC adapter if you’re troubleshooting a tablet or laptop, and possibly a screwdriver if you’re working at a desk
How to fix a computer that shows no sign of power
- Believe it or not, the number one reason a computer won’t turn on is because it wasn’t turned on.
Before you begin a sometimes time-consuming troubleshooting process, make sure that you have turned on all of your computer’s system power switches and buttons:
Power button/switch, usually located on the front of a desktop case, or on the top or side of a laptop or tablet
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Power switch on the back of the computer, usually only on a desk
Power switch on the power bar, surge protector, or UPS, if you’re using one
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- Check for disconnected computer power cable connections. A loose or unplugged power cord is one of the main reasons a computer won’t turn on.
Even if your computer is running on battery power, you should make sure the AC adapter is connected properly, at least during troubleshooting. If you regularly keep your computer plugged in, but it has come loose and the battery is now empty, your computer may not be receiving power for this reason.
- Plug your tablet, laptop, or desktop directly into the wall if you haven’t already. In other words, remove any power strips, battery backups, or other power distribution devices between your PC and the wall outlet.
If the computer begins to receive power after doing this, it means that something you took out of the equation is causing the problem, so you may need to replace your surge protector or other power distribution devices. Even if it doesn’t improve anything, keep troubleshooting with the computer plugged into the wall to keep things simple.
- Perform a “lamp test” to verify power is coming from the wall. The computer will not turn on without power, so make sure the power supply is working properly.
We do not recommend testing an outlet with a multimeter. Sometimes a tripped breaker can leak enough power to show the proper voltage on the meter, leaving you with the assumption that your power is working. Putting a real “load” on the plug, like a lamp, is a better option.
- Check that the power supply voltage switch is set correctly if you are on a desktop. If the input voltage of the power supply unit (PSU) does not match the correct setting for your country, your computer may not turn on at all.
- Remove the main battery from the laptop or tablet and try using only AC power. Yes, it is perfectly fine for your laptop to work without the battery installed.
If your computer turns on after you try, your battery is causing the problem and needs to be replaced. Until I replace it, feel free to use your computer as long as it’s near an outlet!
- Carefully inspect the laptop or tablet’s power receptacle for damage. Check for broken or bent pins and debris that may be preventing the computer from powering and charging the battery.
Aside from straightening out a bent pin or cleaning up a bit of dirt, you’ll probably need to seek the services of a professional computer repair service to correct any major issues you see here. Be sure to remove the internal battery from the laptop to avoid the risk of electric shock if you work on it yourself.
- Replace the computer’s power cord or AC adapter. On a desktop, this is the power cord that runs between the computer case and the power supply. The AC adapter for a tablet or laptop is the cable that you plug into the wall to charge the battery (it usually has a little light on it).
A bad AC adapter is a common reason for tablets and laptops not turning on at all. Even if you don’t regularly use the power cord, if it has failed, it means you haven’t been charging the battery.
A bad power cable is not a common cause of a computer not getting power, but it does happen and it’s very easy to check. You can use the one that is powering your monitor (as long as it appears to be getting power), one from another computer, or a new one.
- Replace the CMOS battery, especially if your computer is more than a few years old or has spent a long time off or without the main battery. Believe it or not, a bad CMOS battery is a relatively common cause of a computer that appears to be not getting power.
A new CMOS battery will cost you less than $10 USD and can be picked up anywhere that sells batteries.
- Make sure the power switch is connected to the motherboard if you are using a desktop. This is not a very common point of failure, but the computer may not turn on because the power button is not properly connected to the motherboard.
Most box switches are connected to the motherboard using a twisted pair of red and black cables. If these cables are not connected securely or not connected at all, this is likely the cause of the computer not turning on. A laptop or tablet usually has a similar connection between the button and the motherboard, but it’s nearly impossible to get to.
- Test your power supply if you are using a desktop computer. At this point in troubleshooting, at least for desktop users, it is very likely that the computer’s power supply is no longer working and needs to be replaced. However, you should try it out just to be sure. There is no reason to replace a piece of hardware that works when tested is quite easy.
A smell of ozone or a high-pitched noise, combined with no power at all to the computer, is an almost certain indication that the power supply is bad. Disconnect your computer immediately and skip the test. Replace your power supply if it fails its test or if you experience the symptoms I just described. After replacement, keep the computer plugged in for 5 minutes before booting to give the CMOS battery time to recharge.
In most cases, when a desktop computer is not receiving power, a faulty power supply is to blame. I bring this up again to help emphasize that this troubleshooting step should not be skipped . The following causes to consider are not as common.
- Test the power button on the front of your computer case and replace it if it fails the test. This is valid only for desktop computers.
Depending on the design of your computer’s case, you may be able to use the reset button in the meantime to turn on your computer.
Some motherboards have small power buttons built into the boards themselves, providing an easier way to test the power button on the case. If your motherboard has this, and it works to turn on your computer, the power button on the case probably needs to be replaced.
- Replace your motherboard if you are using a desktop. If you are sure the wall power, power supply, and power button are working, there is likely a problem with your PC’s motherboard and it needs to be replaced.
While it’s perfectly doable for anyone with a little patience, replacing a motherboard is rarely a quick, easy, or cheap task. Make sure you’ve exhausted all the other troubleshooting tips I’ve given before before you replace your motherboard.
We strongly recommend that you test the computer with a power-on self-test card to confirm that the motherboard is the cause of the computer not turning on at all.
Replacing the motherboard is probably the right course of action at this point with a laptop or tablet as well, but motherboards on these types of computers are very rarely user replaceable. The next best course of action for you is to seek out a professional computer service.
- At this point, your PC should be working again.
Tips and more information
- Are you troubleshooting this issue on a PC you just built yourself? If so, triple check your settings ! There is a good chance that the computer will not turn on due to a misconfiguration and not an actual hardware failure.
- Did we miss a troubleshooting step that helped you (or could help someone else) fix a computer that shows no sign of power? Let me know and I’ll be happy to include the information here.
- Is your computer still not showing any sign of power even after following the steps above? Get more help and information on how to contact me on social media or by email, posting in support forums, and more. Be sure to tell me what you’ve already done to try to fix the problem.