How to troubleshoot motherboard issues – Part I

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ACKNOWLEDGEMENTS: I want to thank dai, tumbleweed36, and all the great TSF Hardware Team. Especially tumbleweed36 painstakingly reviewed this article and provided invaluable comments and insights. All this help is greatly appreciated. The article wouldn't ever be of true TSF standards if it weren't for his feedback.



You have either just finished assembling a computer or you have been using it for some time, and you encounter problems that make you focus on your motherboard’s functionality; this is because your PC either doesn’t boot successfully (locks in the middle of the boot process or posts error messages) – or doesn’t power up or boot at all. Moreover, it could be that your system has simply become unstable, exhibiting frequent crashes. Other peripherals of your PC may come into play as well, but you want to rule out your motherboard as a culprit – here’s what to do.


Before moving on, you need to have an accurate picture of your computer’s configuration.
• In order to identify your motherboard, see step 3 of How to get prepared for the inevitable in Windows XP – Part II.
• In order to gather additional information about your installed components and their respective drivers, see step 2 of How to get prepared for the inevitable in Windows XP – Part I.


CAUTION Please discharge yourself of any static electricity before attempting anything on your motherboard and while you are working. Electrostatic Discharge (ESD), which is a bit annoying but for sure harmless to humans, is certainly lethal to sensitive electronics. (For example, a few steps on a vinyl floor will produce 12,000V of static electricity - many times the destruction threshold of a typical electronic component.) You will be generating static electricity whenever for example:
• You open a common plastic bag.
• You remove adhesive tape from a container.
• You slide a circuit board on a work bench.
• You walk across a floor.
As you can see, rather common actions can potentially have catastrophic consequences. Electrical fields can penetrate electronic devices. ESD is not selective and can damage components directly and indirectly. In order to be on the safe side, the best idea is to use antistatic wristbands (which are also called ESD wrist straps) - especially when handling the processor and the memory chips. You can see an antistatic wristband pictured below. The wrist strap is connected to ground through a coiled retractable cable and 1 megohm resistor, which allows high-voltage charges to leak through but prevents a shock hazard when working with low-voltage parts. If you are willing to invest in an ESD wrist strap, then please do not buy a very cheap one; because typically these do not have conductive fabric and instead use the fabric to hold the metal plate against the skin, which can result in reduced ESD protection over time as the metal corrodes. When using an ESD wrist band, then do not forget to attach its alligator clip to a bare metal part of your computer, workbench or other grounded connection.


If you do not have any ESD wrist straps, then please touch a metallic object to let the static discharge, before you start handling your motherboard. However, while handling the motherboard, avoid touching any metal leads or connectors. If you will need to walk and then continue working on your motherboard, touch again briefly an unpainted metal part of your computer casing, before resuming work.


CAUTION Here are some general best-practice guidelines when working with your motherboard and its components:
• When you intend to remove the motherboard from the computer's case, first turn everything off and unplug the power cord before continuing. When working on portable computers, also remove all batteries, PCMCIA cards and disconnect all peripherals.
• Before unplugging the power connector(s) of the motherboard, verify first that the power supply is switched off.
• Do not use magnetic tools (like screwdrivers etc).
• Prior to installing any electronic component, keep it on top of an antistatic pad or inside an antistatic bag (formally called an electrostatic shielding container).
• Do not allow screws or other metallic parts to come in contact with the motherboard circuit or its components. Moreover, always weed out screws or metallic objects that may have been left inside the computer casing.
• Make sure you place all screws you remove, in a safe place out of the way. Moreover, if the screws you have removed appear to be of various sizes, then keep them in separate spots and take notes regarding where they were removed from.
• Do not remove any of the stickers on the motherboard, because this can void your warranty.
• Have all the relevant documentation handy, and study it before acting.


NOTE Please keep in mind that this is a generic troubleshooting guide for the average user. There is always a chance you might be facing issues that are not covered by the procedure laid out here (especially if you have a motherboard that is very complex/advanced, very old or with a record of extreme incidents). In any case, and particularly if you are evaluating the possibility of discarding your motherboard, please consult the TSF experts at the Motherboards, Bios & CPU subforum. If you have questions or do not understand a term or method described here, please do not hesitate to ask.


A. You press the Power button on your PC, and no message is posted on the screen.

You may be seeing absolutely no indications that your system powers up or you may see only the CPU fan turning. Or you may have positive indications that your system powers up, nevertheless it does not post anything and you are hearing beeping sounds. Another case is your system does power up but shuts down within a couple of seconds. The following is a step-by-step procedure to troubleshoot this kind of incidents to the wider scope possible.


1. Confirm that the computer and the monitor are properly plugged in an outlet or a functioning UPS. (UPS stands for “Uninterrupted Power Supply” and is a device described and explained in step 5 of How to get prepared for the inevitable in Windows XP – Part II.) Confirm that the power switch at the back of your computer (if present) is on (I=ON, O=OFF). Confirm that the voltage selector (if present) is set correctly for your area.


2. Confirm that the monitor is properly and securely connected to your video adapter. If you have positive indications that the motherboard comes alive, yet you see nothing on the screen and you cannot guarantee the good functionality of the monitor in use, then try again your rig with another monitor of known good functionality.

3. Confirm that the motherboard is correctly connected to the power supply.


Older motherboards are powered through the ATX 20-pin connector only:


Pentium 4 motherboards require an ATX 2.03 spec power supply, with an ATX 12V 4-pin connector plugged to the 4-pin power header on the motherboard:


Even newer motherboards are equipped with an ATX 24-pin connector (instead of the 20-pin one) – see the image on the left. Some motherboards permit that either an ATX 24-pin or 20-pin connector is used (notice the cap) – see the image on the right:


4. Eliminate the possibility that the power button of the case is malfunctioning. To do so, you will first need to locate in your motherboard the Front Panel Header. This is an area, shown inside a black circle in the following image, where the wires that come from the front panel of your computer's casing, are connected to the respective pins of the motherboard. Every motherboard has a Front Panel Header (some manufacturers call it a Front Panel Jumper), yet the actual pin configuration differs from one motherboard to the other and you will need to consult its documentation in order to understand the exact layout for your case. Typically, the Front Panel Header will host the following connectors:
• Power Switch, a two-pin receptacle where the connector coming from the casing's power button is plugged. Motherboards and casings typically identify this connector as “POWER SW” or “PW”.
• Reset Switch, a two-pin receptacle where the connector coming from the casing's reset button is plugged. Motherboards and casings typically identify this connector as “RESET SW”, “RESET” or “RES”.
• Hard Disc LED, a two-pin receptacle where the connector coming from the casing's LED that signifies the Hard Disc is active, is plugged. Motherboards and casings typically identify this connector as “HDD LED”, “HDD” or “HD”.
• Power/Message/Sleep LED, a two-pin receptacle where the connector coming from the casing's LED that signifies the computer is powered on, is plugged. Motherboards and casings typically identify this connector as “POWER LED” or “PWR_LED”.
• Speaker, a four-pin receptacle where the connector coming from the computer's speaker is plugged. Motherboards and casings typically identify this connector as “SPEAKER” or “SPEAK”.


So, first use the motherboard's documentation and then inspect visually, in order to locate the pins that correspond to the Power Switch. Remove the power switch connector from the respective pins, and then short those two pins with a small screwdriver (as shown in the picture below). If your computer now posts successfully, your problem was caused by a faulty power button.


5. Verify that the CMOS jumper is set at the “Keep Data” position (pins 1-2):


6. Verify that your power supply has enough wattage to support your system. Use TSF’s exceptional Power Supply Information and Selection advisory – where you will also find a great PSU calculator you can use to see if you are severely underpowered. A word of caution: aforementioned TSF advisory is the greatest tutorial on how to select the best PSU for your system; so, do not take it lightly or for granted that you are covered power-wise simply because your system finally boots up. Having a computer on the edge of being adequately supplied with power can and will lead you to endless problems and issues which may eventually hurt almost all your components (and, mainly, your computer’s functionality and your own mental balance). Buying the best PSU for your computer actually buys you peace of mind.

7. Verify that your power supply is operative. Find another one of known functionality and equal or higher wattage, and try powering your computer with it. Also, keep in mind that a mere statement of the wattage is not enough. For a power supply to be operative, the voltage will have to be within acceptable limits, and the delivered amperes will need to be adequate for the specific rig. Please, take the comment from the previous step into serious consideration and, if you haven’t already done so, study carefully the PSU selection advisory mentioned therein. For advanced troubleshooters, there is also the option of Troubleshooting the PSU with a Multimeter

8. Verify that the CPU that you intend to use is indeed supported by your motherboard. Visit the website of your motherboard’s manufacturer and find the CPU support list that corresponds to your motherboard. If you see in this list and the relevant support documentation that your motherboard supports your CPU only via a BIOS update, then download that newer BIOS version and the respective Flash utility, and follow the instructions that accompany the Flash utility in order to update your BIOS. Beware, though! If you are required to ultimately flash your BIOS then, before moving any further, please read now all the precautions you will need to take, which are explained in step 14 of this process.

9. Verify that the graphics card that you intend to use is working OK and is well seated. If your motherboard has onboard video, retest it with the graphics card removed. If it does not have onboard video, then retest this time using another compatible graphics card of known functionality. If you are using an AGP graphics card, these are typically keyed as shown in the image below, in order to prevent an inadvertent installation on a non-supporting motherboard. However, be advised that this is not adequate prevention for you! There is only one way to know for sure if your graphics card is supported or not; and this is to know its exact type and then check it out in your motherboard’s documentation. Why is this? Because there are two versions of the AGP physical interface, for 3.3 V and 1.5 V cards respectively. The 1.5 V version has a key further away from the external connector, while the 3.3 V version is the opposite. However, some poorly designed older 3.3V cards incorrectly have the 1.5V key, which may result in a burnt motherboard if installed in a AGP 4X/8X slot. So, be very, very careful!

AGP cards are backward and forward compatible within limits. 1.5V-only keyed cards will not go into 3.3V slots and vice versa (but remember what we’ve just told regarding a sad yet catastrophic exception to this rule), though “Universal” slots exist which accept either type of card. AGP Pro cards (rarely used) will not fit into standard slots, but standard AGP cards will typically work in a Pro slot. Some newer cards like nVidia's GeForce 6-series or ATI's X800-series only have keys for 1.5V to prevent them from being installed in older motherboards without 1.5V support. The graphic cores can only handle 0.8V for AGP8x and 1.5V for AGP4x and will be damaged by 3.3V slots. Some of the last modern cards with 3.3V support were the nVIDIA GeForce FX5000-series and the ATI Radeon 9500/9700/9800(R350) – but not 9600/9800(R360). Additionally, moving cards between computers of various CPU architectures may not work due to firmware issues.

10. Verify that your memory specifications are supported by your motherboard and that you have placed the memory modules correctly (well seated in the right slots). You will need to consult your motherboard’s documentation because not all memory/slot configurations are functional; in the image below you can see a relevant excerpt from a specific motherboard’s manual (this is just an illustrative example – your own motherboard may be different):


NB: Version 2.0 of this article will contain here a comprehensive guide on confirming the proper seating of DIMM memory modules. Please check again.



An important note if the memory you are using is SIMM: When installing SIMMs, it is important to remember that most systems (Pentium and newer), require two SIMM modules to make a single bank of memory. Because of this, you need to fill the two slots in a bank with identical modules. However, each bank can hold different size modules. For example, bank 1 (slots 1 and 2) may have two 32MB modules, while bank 2 (slots 3 and 4) may have two 16MB modules. The larger modules must be in the first bank (slots 1 and 2). For most 486-based systems, a memory bank can be single SIMM. Early 486-based systems may require four 30-pin SIMMs to make a single memory bank.

An important note if the memory you are using is 184-pin Rambus RIMMs: These require that all empty memory slots contain a “Continuity Module” (C-RIMM), so you will need to confirm these are also properly in place. In this case, all memory slots are filled (with either a RIMM or a C-RIMM).

11. On motherboards equipped with jumpers to set the FSB speed, verify that the FSB-setting jumpers are in the correct position for your CPU. Consult your motherboard’s documentation to confirm what these settings should be. In the image below you can see a relevant excerpt from a specific motherboard’s manual (this is just an illustrative example – your own motherboard may be different):


12. On motherboards equipped with jumpers to set the Core/Bus ratio, verify that they are in the correct position for your CPU. Consult your motherboard’s documentation to confirm what these settings should be. In the image below you can see a relevant excerpt from a specific motherboard’s manual (this is just an illustrative example – your own motherboard may be different):


13. Eliminate the possibility that your BIOS is incorrectly set. The first thing to do is to clear the CMOS. You can achieve this by unplugging the power cord and then setting the CMOS jumper (see image in step 5 above) to the “Clear CMOS” position (pins 2-3) for about a minute. From this point on, whenever your troubleshooting procedure requires you to retest your motherboard under a different configuration (e.g. other CPU, re-flashed BIOS, etc), you will have to repeat this step before moving on. Some motherboards (like MSI K8NGM-V) are equipped with a specific switch that clears the CMOS (you simply press the button in the middle of the connector top side to clear the data – you can see this switch surrounded with a blue circle in the following image):


An alternative way to clear the CMOS is by removing the CMOS battery with the system unplugged for about ten minutes. The CMOS battery is round and silver, and is retained by a small clip. Be careful when you place it again in its position, to seat it with the correct polarity up:


14. Eliminate the possibility that your BIOS is corrupt. Visit the site of your motherboard’s manufacturer and locate the correct BIOS version for your system, as well as the respective Flash utility, and follow the instructions that accompany the Flash utility in order to re-flash your BIOS. Beware, though! Before moving on, please read very carefully and make sure you fully understand these important things:
• Make sure that the BIOS version you want to flash matches your motherboard model; that is, you haven't downloaded a wrong BIOS version.
• If your BIOS is flash-protected, please do not enable BIOS Flash Protection under Advanced CMOS Setup (AMI BIOS) or Advanced BIOS Features (AWARD BIOS) in the Setup menu.
• Be very careful when flashing your BIOS, because the power should never be interrupted during the process – using an appropriate UPS is highly advisable.
• More and more often nowadays the motherboard manufacturers offer to the users the option of updating their BIOS online; that is, the users can visit the proper website and then update their BIOS in pretty much the same way they update any software they have installed in their computer. However, the BIOS is not just another program. The alleged benefits of this method unfortunately have not been widely verified. On the contrary, there has been an extensive feedback from users complaining that their online-flash attempt ultimately failed and, more often than not, resulted in serious mess-ups in the computer. Although this troubleshooting step relates to non-booting computers that anyhow would not be able to connect to the Internet for an online-flash, this is a prime opportunity to urge the reader to avoid using the online-flash option at any cost, and instead adopt the simple, yet fail-safe Flash operation: In other words, to search and locate the right BIOS version for their motherboard, to also search and locate the correct corresponding Flash utility, and then to manually update the BIOS within DOS (usually with a floppy) in accordance with the utility's instructions.

An alternative option for some modern motherboards is that you are given the capability of recovering your BIOS or booting with a backup BIOS – check your motherboard’s documentation to see if this is applicable in your case. Another option if you do not have Internet access and you do have kept a copy of your BIOS (plus the respective Flash utility if you have an Award BIOS) is to attempt recovering your BIOS in accordance with the following procedures:

a. For AMI BIOS: Rename the desired AMI BIOS file (which normally has an extension signifying its version – e.g. A6712VMS.190) to AMIBOOT.ROM. Insert this floppy disk in the floppy drive. Turn on the system and press and hold Ctrl+Home to force update. Your system will read the AMIBOOT.ROM file and recover the BIOS. When 4 beeps are heard you may remove the floppy disk and restart the computer.

b. For Award BIOS: Make a bootable floppy disk in another PC. Copy the Award Flash utility files & BIOS file to the bootable floppy diskette. Open Notepad and write a command line with the name of your Flash executable followed by a space and the name of the BIOS file. Then save this to the floppy drive and name it as Autoexec.bat. Restart your system with this floppy (it can take two minutes before the screen comes out).

15. If you succeeded in re-flashing your BIOS, yet you are still having issues, move on to step 16. If you cannot successfully program your BIOS after having tried all aforementioned options, it might be that you are facing a failed BIOS chip. However, it could still be another device culpable or the whole motherboard altogether; so it is advisable that you connect your motherboard to a minimum set of known good devices (CPU with its heat sink, one memory module, a graphics card or onboard video, and a floppy drive) on a non-conductive surface and retry flashing your BIOS. If you succeed, you have to troubleshoot your devices and peripherals by continuing the procedure. If you are still unsuccessful, weigh the option of getting a replacement BIOS chip against the option of getting a new motherboard.

16. Now that you have confirmed that your BIOS is OK, eliminate the possibility that your case shorts your motherboard. To do so, remove the motherboard from the case and leave on it only the CPU with its heat sink, the memory modules and the graphics card (or onboard video if present). Most probably you will need to unplug and/or disconnect almost everything before doing this, because you may be running into the danger of causing damage to the components, in case you attempt such a task with everything connected. Keep track of what you unplug or disconnect and from where, and take notes on your motherboard’s manual, which you should always have handy next to you. Moreover, it is highly advisable that you unscrew the power supply from the casing and you place it next to the spot on the bench, where you are going to perform this step of the process. Take carefully the motherboard in your hands and place it on a non-conductive surface. Make sure that the heat sink fan is plugged to the motherboard and that the needed minimal components (RAM and VGA) are properly seated. Plug the power connectors to the motherboard (see step 3 above) and retest to see if any message will be posted. If even at the bare-bones configuration still no message is posted, then move to step 17. If indeed a message is posted when you power the motherboard, then check the case mounting standoffs to verify that they are lining up correctly with the mounting holes on the motherboard and move on to step 21.

17. Eliminate the possibility that a memory module is defective. Repeat step 16 above, this time with one memory module at a time. Be careful to put it in the right slot according to your motherboard’s specification. If you do achieve a post with a specific memory module, keep it in place and start adding devices in accordance with step 21 below. If you still get no post or if your configuration includes a single memory module only, find another supported memory module of known functionality and retest your motherboard. If it posts, it was the memory and you have to replace it.

18. Verify that the CPU Fan is connected to the respective connector. Moreover, make sure the Fan is not defective or obstructed or contacts in anyway the CPU.

19. Eliminate the possibility that the CPU is defective. Find a supported CPU of known functionality and retest your motherboard. If now it posts, and you have confirmed during step 8 above that the nonworking CPU is indeed supported by your motherboard, then you are having a failed CPU. If it still does not post, then move to step 20.

20. Verify that the motherboard is in good shape. Carefully examine it visually to determine if there are any components (even very small ones) on the board that look burnt, meted or partially detached, if any clip (e.g the heat sink retainer) or essential connector is broken, if there are visible traces of the board being scratched or otherwise physically damaged. In addition, carefully examine all capacitors, to make sure they are not bulged or leaking. In the following images you can see some capacitors that exhibit the aforementioned physical signs of failure:

If your motherboard shows any of the above physical damage, then you should consult the TSF experts at the Motherboards, Bios & CPU subforum, in order to be advised on what to do. There are component issues on a motherboard that can be successfully dealt with by a specialized technician, and some other, simpler ones, where an advanced user can rectify minor discrepancies. However, not all repairs will have a justifiable cost, especially for older or generic motherboards; so, do not hesitate to post a question in the Technical Support Forum. If your board has no damage whatsoever, and it still does not post even after the preceding 20 steps, then you are most probably facing a dead motherboard issue.

21. Eliminate the possibility that the issue is caused by a device. Place the motherboard in aforementioned bare-bones configuration (step 16 above) back in the case (do not connect any other peripherals yet) and retest it. If it does not post anything, then it is a short for sure and you have to check the mountings as said above. If it posts again like when it was on the bench, then it is a peripheral issue. So, now you have to find the culpable device. Start connecting one peripheral at a time, with this sequence:

a. Keyboard. If yours is a USB one, you may need to enable it through the System Setup utility. If you have a PS/2 unit and your motherboard supports it, try your set-up with this one first until the troubleshooting procedure is successfully concluded. If, however, your only option is a USB keyboard and you intend, after having concluded this troubleshooting procedure, to use this USB keyboard for a Windows XP installation, then be advised that you can face severe problems, as is explained in this article: Universal serial bus (USB) input devices may not work when unsigned drivers are being installed during Windows Setup

b. VGA card (if you have been testing so far with the onboard video). Do not forget to disable onboard video through the System Setup utility before moving on. Also, keep in mind the compatibility concerns mentioned in step 9 above.

c. Floppy disc drive. When you start adding drives, do not forget to connect them to the power supply and the appropriate data bus. If your floppy cable has a twist, connect your drive to the connector after that twist. If the floppy drive is not working when you attempt booting and its busy light comes on and stays on, then unplug its connector and insert its cable reversely. If the only floppy drive available is a USB one, you may need to enable it through the System Setup utility. However, beware! If you intend, after having concluded this troubleshooting procedure, to use this USB floppy drive for a Windows XP installation, then be advised that the drives which can be used in this case are very specific ones and can be found in this article: A connected USB floppy disk drive does not work when you press F6 to install mass storage drivers during the Windows XP installation process

d. Hard disc drive. Apart from the power connector, do not forget to set its jumpers (Single/Master/Slave) correctly to Single (the image below is for illustrative purposes only – consult your HDD’s documentation). If your HDD supports IDE connect it there, even if you intend ultimately to use it in a SATA/RAID configuration. Even for an IDE drive, you might still need to detect it through BIOS. If it is a SATA-only HDD, then you may need to enable the respective SATA controller through the System Setup utility before moving on.


e. CD-ROM drive. Again, apart from the power connector and the bus cable, do not forget to set its jumpers (Master/Slave) correctly, and that you might still need to detect it through BIOS.


f. Remaining devices. You can continue adding all other devices (mouse, remaining fans, additional drives, PCI cards, etc) one at a time, until you finally spot the malfunctioning one. However, generally speaking it is a good practice to achieve a fully functioning state with your operating system installed first, and then continue with the expansion cards and the additional hard discs. Please keep a very careful eye on installation instructions and restrictions for each one of them. Always consult your motherboard’s and their own documentation before moving to the next step. Do not forget to set the jumpers in the drives according to the current setup each time and to power them correctly. Also, every time you add another component verify that your BIOS settings reflect correctly your current configuration before booting your system. If you move your hard disc to a SATA/RAID controller, confirm that you have configured the relevant BIOS settings correctly.

g. Special considerations. If you have a removable device such as a Magneto-Optical (MO) disk or a USB Card Reader connected to the computer and you intend, after having concluded this troubleshooting procedure, to install Windows XP in this computer, then be advised that in order to avoid trouble you have to follow a specific procedure laid out in this article: Drive letter that is assigned to the primary hard disk partition is not correct when you perform a CD-ROM-based clean installation of Windows XP. If you have an Iomega Zip drive on the same integrated device electronics (IDE) cable as the hard disk drive, then you can run into this problem: "STOP: C0000221 unknown hard error" or "STOP: C0000221 STATUS_IMAGE_CHECKSUM_MISMATCH" error message occurs. Also, avoid having the Iomega Zip drive connected during a Windows XP installation.


B. You are hearing beeps when you power on your motherboard.

Regardless of error messages that might be posted on your screen, you might also be hearing beeps coming from your motherboard. The beeps correspond to specific error codes which, if you successfully decipher, can help you limit the scope of your troubleshooting endeavour to a narrower spectrum of potentially culpable components. Beware, though! The error beep code that your motherboard is emitting, could be linked to a cause deeper than the one actually identified by the beeps themselves – so, resist the temptation of shortcut-fixes and perform thorough troubleshooting if necessary. For example, it could be that you are getting a component error, but the real culprit is an insufficient power supply; in such a case, replacing the component will not relieve you from the actual problem.

1. High/Low tone (siren sound)
This means that your CPU is overheating. Immediately check and verify that the CPU heat sink is properly installed and correctly connected to the power supply.

2. AMI Beep Codes
With AMI BIOS, your computer will give you one short beep when the system boots successfully. Apart from beep code 8, all other error codes are fatal.

Beeps - Error message
1 short: System RAM refresh failure
2 short: Memory parity circuit error
3 short: Base 64KB memory failure
4 short: System timer failure
5 short: CPU failure
6 short: 8042 - Gate A20 (keyboard) failure
7 short: Processor exception interrupt error
8 short: Display memory read/write failure
9 short: BIOS ROM checksum error
10 short: CMOS shutdown register read/write error
11 short: Cache memory error
1 long - 3 short: Conventional/Extended memory test failure
1 long - 8 short: Display/Retrace test failure

3. Award Beep Codes
With Award BIOS, your computer will give you one short beep when the system boots successfully. Beware of the fact that the Award BIOS typically is customized by the motherboard manufacturer, so it may very well be that the generic beep codes cited below either do not exist in your own motherboard, or you are hearing an error code that cannot be found here. It is always highly advisable to consult your specific documentation.

Beeps - Error message
2 short: CMOS setting error
1 long, 1 short: DRAM or Motherboard error
1 long, 2 short: Monitor or display card error
1 long, 3 short: Keyboard error
1 long, 9 short: BIOS ROM error
Continuous long beeps: DRAM error
Continuous short beeps: Power error

4. IBM Beep Codes
In the original/standard IBM set of error codes, your computer will give you one short beep when the system starts the self-test, followed by a Normal Post that indicates it boots successfully.

Beeps - Error message
2 short: Initialization error
1 long, 1 short: System board error
1 long, 2 short: Video adapter error (MDA, CGA)
1 long, 3 short: EGA/VGA Graphics adapter error
3 long: 3270 keyboard adapter error
Repeating short: Power supply or system board problem
Continuous: Power supply, system board, or keyboard problem
None: Power supply or system board problem

5. Compaq Beep Codes
Your computer will give you one short beep when the system boots successfully.

Beeps - Error message
2 short: General error
1 long, 1 short: BIOS ROM checksum error
1 long, 2 short: Video adapter error


The contents of How to troubleshoot motherboard issues – Part II
C. How to troubleshoot no-boot issues when you get a message posted
D. How to overcome instability problems
E. Description of the booting process till the BIOS hands over to the OS