The most common way that a computer "won't turn on" is when the PC actually does power on but doesn't display anything on the monitor.
You see lights on the computer case, probably hear fans running from inside, and may even hear sounds, but nothing at all shows up on your screen.
If your computer is, in fact, showing information on the monitor, but is still not booting fully, see How to Fix a Computer That Won't Turn On for a better troubleshooting guide.
How to Fix a Computer That Turns on but Displays Nothing
Try these common fixes in the order we present them:
Test your monitor. Before you begin more complicated and time-consuming troubleshooting with the rest of your computer, make sure your monitor is working properly.
With the monitor disconnected from your computer, turn it on and off. If the display shows diagnostic information of any kind, you know the display is powered and is capable of displaying content.The 8 Best Computer Monitors of 2021
Verify that your PC has completely restarted and is powering up from a completely powered off state.
A computer may appear to "not be on" when actually it's just having problems resuming from either the Standby/Sleep or Hibernate power saving mode in Windows.
Power off your computer while in a power saving mode by holding the power button down for 3 to 5 seconds. After the power is completely off, turn on your PC and test to see if it will boot normally.
Troubleshoot the cause of the beep code if you're lucky enough to get one.
A beep code will give you a very good idea of exactly where to look for the cause of your computer turning off.
Clear the CMOS. Clearing the BIOS memory on your motherboard will return the BIOS settings to their factory default levels. A BIOS misconfiguration could be why your PC won't start up all the way.
If clearing the CMOS does fix your problem, make sure any changes you make in BIOS are completed one at a time so if the problem returns, you'll know which change caused your issue.
Verify that the power supply voltage switch is set correctly. If the input voltage for the power supply isn't correct then your computer might not turn on completely.
There's a good possibility that your PC wouldn't power on at all if this switch is wrong, but an incorrect power supply voltage might also prevent your computer from starting properly in this way, too.
Reseat everything possible inside your PC.skeeze/Pixabay
Reseating will reestablish the various connections inside your computer and is very often a "magic" fix to problems like this one.
Verify that all the cables are connected correctly. For example, if the onboard video card has been disabled, plugging a VGA cable into it will result in nothing on the monitor even if the computer is powered on. In this case, you'd want to plug the VGA cable into the correct video card.
Try reseating the following components and then test if your computer displays something on screen:Reseat all internal data and power cablesReseat the memory modulesReseat any expansion cards
Reseat the CPU only if you suspect that it might have come loose or might not have been installed properly.
We address this component separately only because the chance of a CPU coming loose is very slim and because installing one is a sensitive task.
Check for signs of electrical shorts inside your computer. If you find then, then you'll need to investigate the causes of those electrical shorts.
Test your power supply. Just because your computer's fans and lights are working doesn't mean that the power supply is functioning properly. The PSU tends to cause more problems than any other hardware and is often the cause of a computer's components to work selectively or intermittently.
Replace your power supply immediately if it fails any test you perform.
After replacing the power supply, assuming you do, keep your PC plugged in for 5 to 10 minutes prior to turning it on. This delay provides time for some recharging of the CMOS battery, which may have been drained.
Do not skip a test of your power supply thinking that your problem can't be the PSU because "things are getting power." Power supplies can work in varying degrees—one that isn't fully functional needs to be replaced.
Start your computer with essential hardware only. The purpose here is to remove as much hardware as possible while still maintaining your PC's ability to power on.
If your computer starts normally with only essential hardware installed, proceed to Step 11.
If your computer still isn't displaying anything on your monitor, proceed to Step 12.
This step is easy enough for a novice to complete, takes no special tools, and could provide you with a lot of valuable information. This isn't a step to skip if, after all the steps above, your computer is still not turning on completely.
Reinstall each piece of hardware that you removed in Step 10, one piece at a time, testing after each installation.
Since your computer powered on with only the essential hardware installed, those components must work properly. This means that one of the hardware components you removed is causing your PC to not turn on properly. By installing each device back into your PC and testing them each time, you'll eventually find the hardware that caused your problem.
Replace the defective hardware once you've identified it.
Test your computer's hardware using a Power On Self Test card. If your PC still isn't displaying information on your monitor with anything but essential computer hardware installed, a POST card will help identify which piece of remaining hardware is causing your computer to not come on completely.
If you don't have and are unwilling to purchase a POST card, skip to Step 13.
Replace each piece of essential hardware in your computer with an identical or equivalent spare piece of hardware that you know is working, one component at a time, to determine which piece of hardware could be at fault. Test after each hardware replacement to determine which component is defective.
If you don't have a POST card or spare parts to swap in and out, you're left not knowing which piece of your essential PC hardware is faulty. In these cases, you have little option than to rely on the help of individuals or companies that do offer these resources.
Still having issues? Try these tips to fix a broken laptop screen.How to Fix a Black Screen in Windows 10