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My computer turns on but it won`t boot. What should I do?

by Tom Cumming


This is the second of my series of FAQs on recovering from disaster-struck PCs. The first one tackled PCs that were completely dead - no signs of life whatsoever. This one moves on to the next stage from this: you switch on the computer, and something happens - the power light comes on, you maybe hear a few beeping noises, something on the screen, but the computer does not appear to load Windows and you cannot actually do anything. This FAQ does not tackle problems further down the line, such as the computer that gets to the Windows splash screen and crashes, or gets to the Windows desktop but crashes. This FAQ is purely related to those problems that occur *before* Windows has started to boot.

If this is your situation, you probably have a hardware problem of some kind. The first job you have to do is work out exactly what the problem is, before you can even think about solving it. If you cannot get into Windows, any of the more day-to-day diagnostic tecniques, such as Device Manager, or any third party programs you may have bought, are of course useless, because you cannot get into Windows to run them. All PCs however have two means of diagnosing hardware failures of this nature:

- Error messages displayed on screen;
- Beep codes.

These are produced by the computer's BIOS, after it has completed the POST (Power-On Self-Test) - a brief check over the PC's most fundamental components, before it tries to boot.

The error messages produced on screen are simply that: a short phrase or sentence, indicating where the problem lies. Beep codes are a series of beeps produced by the PC's internal speaker in a sort-of "morse code" fashion. If you hear such a series of beeps, your motherboard manual will tell you what this means: for example, on my motherboard, eight long beeps means a problem with the graphics card. You will only get beep codes if the fault causes the computer to be unable to display anything on the screen. In other words: if your computer is not working because it is failing the POST (Power-On Self-Test), then you will get *either* an error on the screen, *or* some beep codes.

If you do not get an error on the screen, or any beep codes, this could mean one of several things:

- There is nothing wrong with your PC, but the monitor has broken down, is not connected properly or is not receiving power;
- You cannot see the error message because the monitor has broken down, is not connected properly or is not receiving power;
- You cannot hear the beep codes because the speaker is not connected properly. These beeps normally come out the internal speaker, not the sound card's speakers, except on some machines (especially laptops) where it is wired through the sound card;
- You are reading the wrong FAQ! If you've checked the three things above and you still cannot either see an error message or hear a beep code, then the problem is probably nothing to do with the Power-On Self-Test at all, so you need to move on to the next FAQ in the series (not written yet!) referring to problems booting up Windows.
- The hardware failure is so severe that it is beyond even the beep codes, in which case it is time to seek professional help.

What I am now going to do is talk you through some of the most common error messages and beep codes, and what you can do about them. Please note that the precise wording used for the error messages, and the coding system used for the beep codes, will vary slightly from one machine to the next. For detailed information about your particular machine (or a load of indecipherable nonsense, badly translated from a far-Eastern language, depending on the make of motherboard!!), refer to your motherboard manual. Normally the error messages will also have a number code with them, so that when looking at the manual, or phoning technical support, you can just remember that you've got error number 26 or whatever, instead of having to remember the precise wording.

POST error messages

Unfortunately, these responses don't tend to be terribly helpful, often not giving particularly meaningful messages, so the next job is to work out what it is telling you. Below I have listed some of the most common errors that you can, relatively easily, do something about:

Keyboard error: this indicates that either your PC cannot find the keyboard, or it has found it but there seems to be something wrong with it. This might mean it is not connected properly, one of the keys is jammed down, or you or something/someone was leaning on it when you turned the computer on!


Non-system disk or disk error:
Cannot find operating system:
Missing operating system:
Boot device not found:
Disk 1 failure:
Disk 0 failure:

all variations on the same theme, which is the computer cannot find it's operating system (Windows, normally.) The most common cause of this error is that someone has left a floppy disk in the drive! Most PCs will, if they see a floppy disk in the drive, ignore the hard drive and try to boot from the floppy disk instead, and if the disk does not contain an operating system, then you will not get very far!

If you have not left a disk in the drive, this probably indicates that your hard drive has failed, or is not connected properly. Open up your PC case and make sure that the cables going into your hard drive have not worked loose. There should be two: a wide ribbon cable that carries data (the other end of which should be in the motherboard, possibly via another storage device), and a chunkly 4-wire power connector. Failing that, your hard drive is probably faulty, and needs replacing.

Do bear in mind however, that a lot of hard drives do not fail outright, but in parts. You may find that you have got a few bad sectors right on the boot sector (the first bit that the computer has to read to start up), but the rest is OK. In which case, you may be able to carry on using the same drive for a while, provided it does not get any worse, but you will probably have to repartition and reformat your hard drive, and reinstall Windows (which I would advise leaving to an expert!) to get the drive to boot again. Once you have done this, regularly use Windows' Scandisk program in "thorough" mode, in order to make sure the drive is not deteriorating further.


Memory error:
Parity error:
ECC error:

some kind of problem with the memory. The first thing to try is to remove and reseat the memory, as it may be just a poor connection. Memory is very sensitive to damage from static electricity, so when doing this, turn the PC off at the mains, but leave the plug connected to the wall socket, and regularly touch the inner casing of the PC to earth yourself. In appearance, the memory is one or more small circuit boards, around 15cm long, connected to the motherboard, with a series of identical looking rectangular chips running along one or both sides of the circuit board. What you need to do, is with each one in turn, carefully remove them and replace them again. There will normally be a pair of small clips either side of the memory sticks to hold them in place.

If this does not work, this indicates that one or more of the memory sticks is damaged. It is now time for some trial-and-error: you need to start removing one at a time, and find the faulty one by a process of elimination. Only it is not quite as simple as that! There are a couple of complications:

1. Most PCs require the memory slots to be filled in order, starting from slot one and working upwards. So once you have taken one out, you have to move all the others up one slot, so that there are no empty slots between two filled ones.

2. Some memory types have to be installed in pairs, or in groups of four, where each stick of memory in the group has to be identical. Your motherboard manual will tell you if this applies to you. If so, then you will have to add and remove the memory in pairs or fours.


Time and date not set: Your system clock has not been set. Unless it is a brand new PC, then this probably means the battery that keeps the clock going has run out. It should then let you press a key to set the time and date up again, or let you boot Windows and set them, but if the battery is flat you will have to do this every time. So get the battery replaced!


System options not set:
Similar to the above, but the computer has also lost some of it's BIOS configuration, because of a flat battery, and they have been reset to factory settings. Your computer will probably still boot, but may not be configured for optimal performance this way. So again, you need to replace the battery, and refer to your motherboard manual for all the various BIOS settings, how to set them, and what they all are for. They vary enormously from one machine to the next, so there is not a lot of point in me going into any detail here.


There are lots of other POST error messages, but I am going to leave it at that, because just about anything else will indicate a fairly major hardware failure and will probably be time to take the machine in for repairs.

Beep codes

To tackle this one I am going to refer to a sheet I printed off the internet, listing the AMI BIOS beep codes. AMI (American Megatrends Incorporated) is one of the largest manufacturers of PC BIOS chips, and these are the codes that most their recentt motherboards use. If you do not have a motherboard with a BIOS chip made by AMI, then your beep codes will probably be different, so you will need to look in your motherboard manual, or the BIOS maker's website. However, the kinds of errors you can get will be similar, as will be the solutions. What I am now going to do is to list what AMI say for each beep code, and then explain what this means to you:

1 beep : Refresh failure
2 beeps : Parity error
3 beeps : Base 64k memory error
4 beeps : Timer not operational
5 beeps : Processor error
6 beeps : 8042 - gate A20 failure
7 beeps : Processor exception interrupt error
8 beeps : Display memory read/write failure
9 beeps : ROM checksum error
10 beeps: CMOS shutdown register read/write error
11 beeps: Cache memory bad

1, 2 or 3 beeps all refer to problems relating to the memory. See "memory error" above, in the error messages section.

4, 5, 7 or 10 beeps mean problems with the motherboard, so it needs to be sent in for repairs.

6 beeps: This is what the AMI site says: "For six beeps try reseating the keyboard controller chip. If the error still occurs, replace the keyboard chip. If the error persists, check parts of the system relating to the keyboard, e.g. try another keyboard, check to see if the system has a keyboard fuse." I have no idea even what a keyboard controller chip looks like, so if I were you, I would try another keyboard, and failing that, send the PC in for repairs.

8 beeps means a problem with the graphics card's memory. It is quite common for graphics cards just to work very slightly loose, so you may find just removing and reinserting the graphics card will do the trick. You can easily tell which card is the graphics card: it is the one the monitor plugs into! When doing this, watch out for a fastening clip behind the card. A lot of modern cards have a clip behind them to hold them in place, so don't just pull it, or it might snap in half! Unfortunately, the memory on most graphics cards is not removeable, so if this does not work, it is probably time for a new graphics card.

If you are now looking inside your PC completely bermused, thinking you have not got a graphics card at all, don't worry. You probably have what is known as an "onboard" graphics adaptor, or one that is built into the motherboard, and not mounted on a seperate card. These usually use the computer's main system memory, so to check the system memory, see the bit on memory errors above. If this does not work, you will need to replace your motherboard, and that is a job best left for the experts.

9 beeps indicates faulty BIOS chips. Don't even think about trying to fix this yourself: send it in for repairs.

Copyright © 2001-2006 © Copyright Karl Davis.

No part of this site may be reproduced in any format.All documents author acknowledged are copyright retained by the author.

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