James Hunt provides some essential advice for getting your PC up and running again
When you use a computer, you learn to take things for granted. You might not know how your processor works, but you trust that it will, and that if it doesn’t, something will notice before you do. You’ll get an error message or an alarm or some other warning that things aren’t working as they should be.
Unfortunately, this doesn’t extend to all areas of computing. One of the simplest things users take for granted is that when you press the power button, your system will come alive and boot into your operating system so you can start using it. But what if that stops happening? Where do you even start to fix things? If you’re not sure what the answers to those questions are, you should be by the end of this article.
The hardest problem to diagnose is a very simple to explain one: you press your power button and nothing happens. If you’ve ever tried to help someone fix their own PC, the phrase ‘nothing happens’ can be a very loaded one, of course. Sometimes it means ‘Windows doesn’t respond to my inputs’, and sometimes it means ‘nothing appears on the screen and the computer beeps a lot’. But we’ll take it to mean what it literally does: you press the power button and nothing happens. No fans, no hard drive spinning up, no picture on the screen. Nothing. It’s one of the more terrifying things that your computer can do, but there’s actually good news: it’s quite likely that it’s nothing severe. But what might it be? Here’s how you find out.
Eliminate The Obvious
Not to get too Sherlock Holmes on you, but if you hit the power button and nothing happens, the first thing to do is make sure the simplest explanations are accounted for. An unresponsive power button might be the result of any number of problems, so crossing them off the list is the only way to find what the actual problem is.
The most obvious questions take the least time to answer, so start with them. Is your system still plugged into the mains? Is the power socket switched on? Is the power socket actually working at all? If the mains ring has tripped or a power cut has occurred without you noticing, that might account for the problem. Test the socket using a different appliance, such as a lamp. If you’re using a multiplug, bypass that and go straight to the mains. Once you’ve verified that the wall is providing power, you’ve at least eliminated one line of investigation.
The next step is to check your PC. If power is definitely available at the wall, you need to find out when it’s not getting to your system. Check that the power cable and/or kettle lead is properly plugged in. If you’re looking at a desktop system, the PSU may have a master switch, so make sure that’s set to the ‘on’ position. If all of these things are properly set up, then good news: you have the simplest part of the investigation out of the way and are well on the way to finding out what might actually be wrong.
At this point, it’s a good idea to test a spare power cable or kettle lead if you have one. If the mains socket is working and the power connections aren’t impeded, there’s every chance that the lead itself has been severed or that the fuse has gone in the plug socket. Swapping cables will quickly let you check whether that’s the case. If you don’t have a spare lead, it’s probably worth replacing the fuse with a fresh one if you have the ability to do it quickly. There’s no downside to having a fresh fuse in place, and it’ll eliminate the possibility that the lead is to blame, to a reasonable extent, since kettle leads are hardy enough that they shouldn’t be severed under normal use.
If you’ve checked all this and the power still doesn’t work, then at least you can be sure that the obvious problem – that the computer isn’t actually getting any power – has been dealt with as fully as possible. Unfortunately, the options that remain are more technical and will require you to crack open your PC. Get ready for some invasive procedures.
Checking The Power Button
If the power button doesn’t work and you’ve established that there isn’t a problem between the PC and your mains supply, the fault can only be inside your system. There’s no way to determine what the problem might be other than testing the components. When you press the power button, it triggers a signal on the motherboard, which sends a signal on the PSU. If the signal is interrupted, your PC won’t switch on. Finding out why and where the signal is being interrupted is what we’re trying to do, so again it’s probably worth checking them in order of difficulty.
The first thing to look at is the power button. Inside your case, you should be able to find wires running from the power button to your motherboard. If you can’t, they may have become dislodged or severed somehow, and there’s your problem, but either way it’s worth checking that they’re fine. The leads are normally in pairs of black and red, with a two-pin connector at the end, but they might be colour coded or bundled into larger connectors.
Once you’ve located them, check that the leads haven’t been cut or otherwise broken. If they have, you’ll need to replace the entire power button unit. If the leads seem fine, check that they’re connected to the right place on the motherboard. For most systems, you’ll see one connector labelled ‘power’ and one labelled ‘reset’. They connect to pins on the motherboard (usually labelled ‘front panel’), though you may need to check your motherboard manual to make sure which ones.
If the power previously worked but has suddenly stopped, it’s unlikely the pins are incorrect, but it could indicate a fault with the wires. One easy way to test is to swap the power and reset plugs over, which will essentially turn your reset switch into a power button. If that works, at least you know the fault is with the power button rather than anything else (remember to swap the pins back, though!). If that doesn’t work, you can try removing the power switch plug and connecting the pins using a jumper cover or (insulated) screwdriver. This will send an ‘on’ signal, allowing you to bypass the switch itself.
And if none of those things work, then it’s unlikely the problem is with the switch itself. Which means you may be in for some bad news, because there are only two things left to check: the motherboard and the PSU.
Checking The PSU & Motherboard
At this stage there’s no easy way to tell whether the PSU or the motherboard has broken, but the PSU is easier to get to and replace if anything has gone wrong.
Start by checking the power connection to the motherboard. This is a 20/24-pin ATX connector. Again, if your PC did work but now doesn’t, it’s unlikely this is installed incorrectly, but on new builds it’s surprisingly easy to miss. It could also have been loose and knocked free somehow, though this is a long shot, because the ATX connector has its own clip to keep it in place and oriented correctly.
If this connector is fine, then it’s likely that either your motherboard or PSU has broken and needs replacing. There’s a slight possibility that the system is trying to draw too much power to start, so you can try unplugging unnecessary components, but at this point it’s more likely that something has failed. If you have a spare PSU available, now’s the time to dig it out (although don’t use a second-hand PSU permanently, as they’re more prone to damage and failure depending on how old they are).
If you don’t have a spare PSU, you’ll probably have to buy one to see if your current one has broken, but it is possible to perform a quick test. All you need is a power-supply tester (which you can buy at retail) or, if you’re feeling daring, a paperclip and some electrical tape.
If you want to take the latter approach, then for obvious reasons, you need to take care if you want to avoid an electric shock. Keep the PSU unplugged until you’re ready to test it and make sure not to touch any exposed metal while the clip is plugged in. If you make a mistake the shock should only be 24 volts, but that’s not to say there’s any safe amount of electric shock to take!
To perform the test, simply bend the paperclip straight, wrap it in insulating tape leaving a small amount of exposed metal at each end, then bend it into a U
shape so you can slip it into the 24-pin ATX connector causing the green and black wires to link up. With the plug in place, switch the PSU on, and if it works the completed circuit will allow it to power up as normal. If it doesn’t, the PSU is likely broken and at least if you spend money on a replacement, you know it’ll be worth the expense.
If this works, then assuming you’ve followed all of the previous steps and ruled out problems with the mains supply, the power cables, the PSU, the power switch and the power switch cables, then we’re left with only one other possibility: motherboard failure. This is the most expensive and difficult problem to address, which is why we’ve left it until last, but luckily there’s only one thing you can do: buy a new motherboard.
So get online and find a replacement, then get ready to dismantle your system, because there’s not much else you can do at this point. If you want to double check for faults again, that might be a good idea – if you don’t, you might find that you replace your motherboard and still nothing happens, so you want to be absolutely certain that’s what has gone wrong before you spend the money and put in the work!
Failure To Reach POST
As alluded to in the introduction of this article, there are other ways your computer can fail to respond when you push the power button. If your system is getting power but still won’t boot, there are a few obvious causes worth investigating, and it all depends at what point the failure occurs.
For example, if you push the power button and your system powers up, you know that the PSU, motherboard and power button are probably working fine. The next thing you should hear is the POST beep and a boot screen. If that doesn’t happen, you’re left with nothing but spinning fans, whirring hard drives and a problem to solve.
Usually, this state is caused by a processor that isn’t functioning properly. Without the CPU, your motherboard is little more than a chunk of circuitry, and while beep codes can indicate a problem with any other mandatory component of your system, you’ll only hear them if the CPU is working.
If the hardware goes no further than powering up, switch it back off and check that your processor is seated properly. If that still doesn’t work, it’s possible there’s a major fault with either the CPU or the way the motherboard communicates with the CPU, neither of which is an easy problem to diagnose. Check or obvious problems, like damage on the motherboard or processor, and if you can’t spot anything, you’ll have to find some way of eliminating one possibility.
It’s easier to swap out a processor than an entire motherboard, so if you have access to a spare system with a compatible socket, swap your CPU into it and see if it works. If you haven’t, you could to just buy a new CPU and hope it’s not the motherboard that’s died – although it might be worth using the excuse to upgrade your processor and motherboard combination anyway.
It’s worth noting that before you try spending hundreds of pounds on new hardware, the problem might still be with your PSU. If your PSU isn’t supplying enough power – for example, because you have a particularly powerful graphics card – then it’s possible for your system to switch on even though there isn’t enough electrical capacity to initiate a proper boot sequence: fans and smaller components get powered, but the CPU doesn’t. To check for this, simply unplug any powerhungry components and/or try another PSU if you don’t have one available. This is a rare phenomenon, though, so don’t put too much stock in it unless you’ve eliminated all the others.
Beep Codes
If your system pauses after boot has begun, you should have a much easier time of figuring out what a problem is, not least because you should have access to the beep codes.
If you’re not sure what this refers to, that’s probably because you’ve been lucky. Nonetheless, you should be familiar with at least one beep code: the one that tells you your system is fine – a single short beep from the PC speaker, which occurs with every fresh boot. If you’re lucky, you’ll never hear another.
If you’re unlucky, you’ll hear a succession of different beeps. You might hear four long beeps, two short ones, two short then two long or any number of other patterns. You’ll have to check your motherboard manual, but the pattern of beeps will indicate where in your system a fault lies. Specific patterns might correspond to severely faulty RAM or a missing graphics device or even a problem with the BIOS. They can be quite specific, which means if you know what the code refers to, it’s normally easy (if not necessarily cheap) to fix the problem.
The important thing to be aware of is that beep codes aren’t the same from manufacturer to manufacturer and, indeed, they can even differ between versions of the same hardware model. Make sure when you look up the code that you’re checking the codes for the right system, otherwise you could end up trying to fix the wrong problem.
And once the problem has been addressed, your computer is free to start the boot sequence – which is the next place things can go wrong.
Boot Failure
In order to start up, your computer looks for a boot sector (also sometimes called a boot record) on the main hard disk. This tells it various things about how to proceed. Generally speaking, a boot disk failure occurs when the boot sector can’t be found, but the next step is determining the reason why. Assuming that you actually have a drive installed, there are a few possible causes of boot disk failure.
The most common (and most devastating) is that there’s a physical fault with the disk. There’s very little you can do in this circumstance, other than replace the disk and maybe send it off to a data recovery centre if your backups aren’t up to date. Physical disk faults are fairly easy to notice on mechanical hard drives because the disk will probably sound broken, but if you’re unsure (or you have an SSD), then try it in another machine before sending it to the dump. You might get lucky.
If the hard drive isn’t displaying any obvious signs of damage, then the problem might be that your PC is trying to boot from an inappropriate device. Most PCs are configured to check for USB devices and bootable CDs before a bootable hard drive so in the case of a serious error you can use a recovery disk. As a result, however, you can find your PC claiming that the boot device is corrupt or unusable when what it actually means is ‘This USB thumbdrive should have been unplugged before you hit restart’.
If your computer is definitely trying to boot from the correct hard drive, the next most likely cause of failure is that the boot sector is corrupt. Only a very small (if specific) amount of data needs to be damaged for this situation to arise, and in the vast majority of cases, the rest of the information on the drive won’t have been deleted at all; you just can’t get to it if you can’t boot into an operating system.
The quickest way to repair the boot sector is in the Windows Recovery Console. Boot from your Windows CD or rescue disk, enter the recovery console and enter the appropriate commands for your version of Windows. It’ll probably be either ‘fixboot’ or ‘fixmbr’, so look those up and see which matches your particular installation. If successful, these commands write a new boot sector to the current system partition (which you will recognise as your ‘C:’ in Windows). You then only need to remove the Windows boot disc and use the command ‘exit’ to restart your machine, at which point Windows should restart normally.
Beware that, if you have more than one operating system installed and in use, the fixboot/fixmbr command will probably render them inaccessible – but then if you’re the kind of person running a dual boot, you probably know that already. For most users, this limitation won’t be a concern.
If these attempts fail, there’s a chance that the data on the disc been wiped or lost, but even that isn’t the last word. An undelete program may be able to recover some or all of the data that was stored on it, but since the undelete process is lengthy and requires the use of thirdparty software, it makes most sense to do it from a Windows environment. Try booting your operating system off a CD or thumbdrive, and you should then be able to access the disk without writing data to it. Once you’ve recovered your files, you’ll probably have to reinstall Windows, but at least your system is working again!
Ultimately, repairing a broken PC is a potentially rewarding experience that, among other things, has the ability to teach you a lot about what’s going on behind those loading screens and startup messages. Take things slow, and keep in mind that there’s no such thing as an unrecoverable error. Only a hard drive crash can really destroy your data, and those are comparatively rare occurrences. Anything else is just an obstacle to overcome, and as long as you pay attention to the error messages you see and proceed in a logical manner, it’s almost always possible to bring your computer back from the brink. And once you do, every time you hit the power button and your computer starts up normally, you’ll feel all the more grateful for it.