Fix a PC Which Won't Boot

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There are few things more frustrating than a computer that won't boot up. Troubleshooting boot issues on a PC can be difficult, because there are so many factors at play, both software and hardware. Determining where to start with a quick diagnosis will help save you a lot of time repairing the problem.

Steps

Diagnosing the Problem

  1. Try to turn on the computer. The first step to determine what you'll need to do is to try to turn the computer on.
  2. Click one of the following links based on what happens.
    • Fix-a-PC-Which-Won't-Boot - Click here if you can't hear any fans starting and can't see anything on the screen, or the computer starts for a moment and then freezes or turns off.
    • Fix-a-PC-Which-Won't-Boot - Click here if your computer doesn't pass the POST (Power On Self Test). This is usually indicated by the lack of a beep and a failure message, or by a series of beeps to indicate an error code.[1]
    • Fix-a-PC-Which-Won't-Boot - Click here if your computer completes its startup sequence but fails to load Windows.

Fixing a PC That Won't Start

  1. Check the power cable. It may seem simple, but double-check that the power cable is plugged in and the outlet is working.
    • Plug the computer directly into the wall to see if your surge protector or power strip is the cause of the problem.
    • If you are using a laptop, make sure that the power adapter is securely connected.
  2. Remove your laptop's battery and connect the power adapter. You can run your laptop without a battery inserted as long as you are plugged into a power source. If your laptop turns on when the battery is removed, something is wrong with the battery and you should contact the manufacturer for a replacement.
  3. Try a different monitor. If your computer is starting up but you can't see anything, there could be something wrong with your monitor. Double-check the monitor's connection, and try plugging in a different monitor if possible.
  4. Open the computer. In order to check the connections inside and to test the power supply, you'll need to open the case. Open-a-Computer.
    • Remember to ground yourself with an antistatic wriststrap or by touching the exposed metal of the case before touching any internal components.
  5. Check your power supply cables. Ensure that the cables that connect your power supply (the box that your power cable is attached to) to your motherboard are securely connected.
  6. Test your power supply. Old power supplies have a tendency to fail, but testing them is a relatively straightforward process. Power supplies are the most common cause for problems with a computer's boot sequence. Check-a-Power-Supply.
  7. Replace your power supply. If your power supply doesn't work after testing it, you'll probably need to replace it in order to get your computer working again. Install-a-Power-Supply.
  8. Check for loose screws. If a screw has come loose in your case, it could be causing your motherboard to short out. Gently rock your case back and forth and listen for metal rattling. Either use your fingers or a long pair of tweezers to remove the screw from the case.
    • Look for any cables that have lost their protective coating, as exposed wiring may be causing a short as well. Replace any cables that have decayed too much.

Fixing POST Problems

  1. Listen to the beep code. If you're "lucky", your computer will issue a series of beeps when it fails to turn on. Look up your motherboard's manufacturer and find the beep code translations. Knowing what the codes mean will make tracking down the problem much easier.[2]
    • Beep codes are unfortunately different for every manufacturer, so you'll need to search for them yourself.
    • Identify-the-Motherboard.
  2. Try opening your BIOS. If you can, try entering your BIOS settings menu as soon as your computer starts. Typical BIOS setup keys include F2, F10, F11, and Del.
  3. Check that all of your hardware is detected. Your BIOS will display all of your connected hardware in the MONITOR, HARDWARE, or SYSTEM section. Check to see that your hard drive is displaying properly.
    • If your hard drive is not showing up, try replacing the cable inside the computer.
  4. Open the computer. In order to check the various components inside the computer, you'll need to open the case. Unplug everything from the back and remove the side panel to access the internal components. Open-a-Computer.
    • Remember to ground yourself with an antistatic wriststrap or by touching the exposed metal of the case before touching any internal components.
  5. Reseat all of your components. Open up your computer and reseat your graphics card, RAM modules, and all of your cable connections. If anything has come loose, there's a chance that it's disrupting the POST sequence.
    • You can try reseating your processor as well, but this is usually a much more difficult task, and likely isn't the cause of the problem. It also increases the chances of damaging the processor, which will render your computer completely inoperable.
  6. Test your RAM modules. There's a chance that a bad memory module is causing your computer to not boot. Try removing memory modules one at a time and booting your computer to try to isolate a bad memory stick.
    • You can Test-PC-Ram-with-MemTest86 to help determine which of your memory modules is failing.
  7. Try removing your graphics card. If you have a dedicated graphics card, try removing it and plugging your monitor into your motherboard's display connection. A malfunctioning graphics card can cause your computer to not boot.
    • Install-a-Graphics-Card.
  8. Remove all unessential hardware. Try booting your computer up with only the most basic hardware attached. This means disconnecting your graphics card, additional drives, PCI expansion cards, and extra RAM. After you've removed everything, try turning your computer on.
    • If your computer works with only the essential hardware installed, add pieces back one at a time, testing each time to see where the problem lies.
    • If you still cannot pass POST with just your essential hardware, then you'll need to either swap out the essential hardware with spares, take your computer to a repair shop, or upgrade to a new one.

Fixing Windows Boot Issues

  1. Open the Advanced Startup menu (Windows 7 and later). If you are having problems loading Windows, you can try to fix it using Startup Repair. This is accessible from the Advanced Startup menu if you are using Windows 7 or later. If you are using Windows Vista or XP, you'll need to Boot-a-Computer-from-a-CD to access the Startup Repair tools.[3]
    • You can open the Advanced Startup menu by repeatedly pressing F8 as the computer starts up.
    • If you can't access the Advanced Startup menu, you may have a problem with your hardware. See the above sections for troubleshooting your boot issues.
  2. Select "Repair Your Computer" or "Launch Startup Repair". You will have to wait a few moments while the necessary files load.
  3. Log in with your administrator account. You will be prompted to log in before you can start the repair process.
  4. Select "Startup Repair". Windows will scan for problems related to booting the operating system and will attempt to fix them automatically. Your computer will likely reboot during this process, possibly multiple times.
    • If Startup Repair fixes something, it is highly recommended to run it at least two more times before trying to boot normally. Chances are it will fix something else when it runs again.[4]
  5. Perform a "System Restore" if Startup Repair fails. Startup repair may suggest performing a System restore, or you can select it from the main Repair menu. System Restore will provide several dates that you can try rolling back to.
    • Always try the most recent date available first, and the move backwards until you find a working restore point.
  6. Reinstall Windows. If none of the repair options work, your only remaining option may be to reinstall Windows. This will erase everything on the hard drive, so it is only recommended as a last-ditch option.
    • Install-Windows-7.
    • Install-Windows-8.
    • Install-Windows-Vista.

Video

Warnings

  • As with any device that plugs into wall current, if during testing you smell ozone or burnt plastic, or hear a "popping" or arcing noise, unplug the device immediately. Unless you know how to work with electricity safely, an internal short is best repaired by professionals.
  • Always turn off and unplug the PC before touching, adding or removing parts within the PC.
  • Wear an anti-static wrist band or ground yourself by touching the case while the system is plugged in.

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Sources and Citations