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BIOS Beep Codes

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					             Computer Hardware Trouble Shooting
                               or
     The computer won’t work!!! – Now what am I going to do?




Basic steps for diagnosing computer problems:
    1.  Look and listen – the computer will give you some hints about what is wrong with it –
        usually in lights, sounds or messages on the monitor screen
    Example:
    Turn on the computer
    a) Are there any case lights? – possible power supply problem (did you plug it in?)
    b) Is there any sounds coming from the case (case fans whirring, etc.) – if not – possible
        power supply problem
    c) Are there case lights and a fan turning, but no beeping – usually a bad CPU that needs
        replacing.
    d) Is the computer beeping? If it is – then it’s trying to tell you what’s wrong
    e) Is there a message on the monitor screen? This means that the CPU, RAM and video
        card are working – a possible problem with the hard drive (HDD Controller error – a
        change in hard disk parameters) or the floppy drive.
    f) Consult the flowchart ( PC repair poster.pdf)

    2.   Common BIOS beep codes (case lights and fan movement present):
              a) No beep – possibly a bad CPU or RAM short
              b) 1 beep – GOOD – everything is working
              c) 1 long constant beep – RAM error – make sure it is seated well
              d) 1 long – 3 short – Video card error – make sure it is seated, or replace the
              defective card.
              e) 2 short – usually means a change in the system BIOS

When a computer starts, it goes through the following sequence during power-up
Power supply, CPU, RAM, Video, floppy drive, hard disk. We need to know this to test the
machine if there is power, but no beeping. Take out all parts and add to get beeps. Example –
power supply + CPU should give a RAM error – if not we have a dead CPU. If we get a RAM
error then add RAM – should get a video error – no? = RAM short. If there is video, then there
likely is a short in one of the peripheral cards (sound, network, etc – insert one at a time to see
the problem) or the HDD cable might be on backwards (will short some motherboards)

More BIOS beep codes are listed on the following pages for usual makes of computers.
BIOS Beep Codes

  What is a BIOS Beep Code? When you power on a computer the BIOS immediately
takes control of the computer and performs the P.O.S.T (Power On Self Test). At the end of the
POST the computer will play an audible 'BEEP' through either the PC's internal speaker of
through speakers attached to the sound card (if you have a built-in sound chip). If the POST
completed successfully without detecting any problems with then system will play a single short
beep to let you know the test is complete and the computer will continue to start up and load the
operating system.

If during the POST the BIOS detects a problem it will normally display a visual error message on
the monitor explaining what the problem is. However, if a problem is detected before the BIOS
initializes the video card, or a video card is not present or not detected then the BIOS will play
several 'BEEPS' through the speaker to let you know there is a problem. Depending on the type
of the BIOS you have the BIOS may play beeps in a specific pattern to indicate what the problem
is, or play the same beep a number of times indicating the problem. It is very important that you
pay close attention to the number and/or pattern of the beeps your computer plays on startup.

 Below is a table of the most common AMI, Phoenix, Award, Compaq Dell and IBM BIOS beep
codes.

 AMI (American Megatrends International) BIOS Beep Codes. AMI BIOS uses beeps of the
same length and pitch. The error is displayed as a number of beeps. For example, 4 beeps
indicated a timer failure.

BEEP CODE                          MEANING                        POSSIBLE CAUSE
 1 Beep (No video)                 Memory refresh failure        Bad memory
 2 Beeps                           Memory parity error           Bad memory
 3 Beeps                           Base 64K mem failure          Bad memory
 4 Beeps                           Timer not operational         Bad motherboard
 5 Beeps                           Processor error               Bad processor
 6 Beeps                           8042 Gate A20 failure         Bad CPU or Motherboard
 7 Beeps                           Processor exception           Bad processor
 8 Beeps                           Video memory error            Bad video card or memory
 9 Beeps                           ROM checksum error            Bad BIOS
10 Beeps                           CMOS checksum error           Bad motherboard
11 Beeps                           Cache memory bad              Bad CPU or motherboard

Award BIOS Beep Codes Award BIOS uses beeps of varying duration. A long beep will typically
last for 2 seconds while a short beep will last only 1 second. Award BIOS also uses beeps of
different frequency to indicate critical errors. If an Award BIOS detects that the CPU is
overheating it may play a high pitched repeating beep while the computer is running.

BEEP CODE                          MEANING                        POSSIBLE CAUSE
1 Long, 2 Short                    Video adapter failure         Bad video adapter
Repeating (Endless loop)           Memory error                  Bad memory or bad connection
1 Long, 3 Short                    Video adapter failure         Bad video adapter or memory
High freq. beeps (while running)   CPU is overheating            CPU fan failure
Repeating High, Low beeps          CPU failure                   Bad processor
Phoenix BIOS Beep Codes Phoenix BIOS uses beep code patterns to indicate problems. In
the table below the '-' indicates a brief pause between beeps.
Example: 1 - 1 - 2 would sound like BEEP <pause> BEEP <pause> BEEP BEEP
 BEEP CODE                          MEANING                    POSSIBLE CAUSE
1-1-2                        CPU / motherboard failure       Bad CPU / motherboard
1-1-3                        CMOS read/write failure         Bad motherboard
1-1-4                        BIOS ROM failure                Bad BIOS chip
1-2-1                        Timer failure                   Bad motherboard
1-2-2                        DMA failure                     Bad motherboard
1-2-3                        DMA failure                     Bad motherboard
1-3-1                        Memory refresh failure          Bad memory
1-3-2                        64K memory failure              Bad memory
1-3-3                        64K memory failure              Bad memory
1-3-4                        64K memory failure              Bad memory
1-4-1                        Address line failure            Bad memory
1-4-2                        Parity error                    Bad memory
1-4-3                        Timer failure                   Bad motherboard
1-4-4                        NMI port failure                Bad motherboard
2-1-1                        64K memory failure              Bad memory
2-1-2                        64K memory failure              Bad memory
2-1-3                        64K memory failure              Bad memory
2-1-4                        64K memory failure              Bad memory
2-2-1                        64K memory failure              Bad memory
2-2-2                        64K memory failure              Bad memory
2-2-3                        64K memory failure              Bad memory
2-2-4                        64K memory failure              Bad memory
2-3-1                        64K memory failure              Bad memory
2-3-2                        64K memory failure              Bad memory
2-3-3                        64K memory failure              Bad memory
2-3-4                        64K memory failure              Bad memory
2-4-1                        64K memory failure              Bad memory
2-4-2                        64K memory failure              Bad memory
2-4-4                        64K memory failure              Bad memory
2-4-4                        64K memory failure              Bad memory
3-1-1                        Slave DMA failure               Bad motherboard
3-1-2                        Master DMA failure              Bad motherboard
3-1-3                        Interrupt controller failure    Bad motherboard
3 - 1 -4                     Slave IC failure                Bad motherboard
3 - 2 -2                     Interrupt Controller failure    Bad motherboard
3-2-3                        <RESERVED>
3-2-4                        Keyboard control failure        Bad motherboard
3-3-1                        CMOS batter failure             Bad CMOS battery
3-3-2                        CMOS configuration error        Incorrect setting
3-3-3                        <RESERVED>
3-3-4                        Video memory failure            Bad video card or memory
3-4-1                        Video init failure              Bad video card or memory
4-2-1                        Timer failure                   Bad motherboard
4-2-2                        CMOS shutdown failure           Bad motherboard
4-2-3                        Gate A20 failure                Bad motherboard
4-2-4                        Unexpected interrupt            Bad processor
4-3-1                        RAM test failure                Bad memory
4-3-3                        Timer failure                   Bad motherboard
4-3-4                        RTC failure                     Bad motherboard
4-4-1                        Serial port failure             Bad motherboard
4-4-2                        Parallel port failure           Bad motherboard
4-4-3                        Coprocessor failure             Bad motherboard or CPU.
9-2-1                        Video adapter incompatibility   Use a different brand of video card
Compaq BIOS Beep Codes: - difficult since most models have different beep codes

  Beeps             Error Message                                    Description
1 short       No error                         System is booting properly
1 long, 1                                      The contents of the BIOS ROM to not match the expected
              BIOS ROM checksum error
short                                          contents. If possible, reload the BIOS from the PAQ
2 short       General error                    Unknown
1 long, 2                                      Check the video adapter and ensure it's seated properly. If
              Video error
short                                          possible, replace the video adapter
7 beeps (1
long, 1s, 1l,
1 short,
                                               The AGP video card is faulty. Reseat the card or replace
pause, 1      AGP video
                                               it outright. This beep pertains to Compaq Deskpro systems
long, 1
short, 1
short
1 long
neverending                                    Memory error. Bad RAM. Replace and test
beep
1 short, 2
              Bad RAM                          Reseat RAM then retest; replace RAM if failure continues
long


  Dell BIOS Beep Codes:

   Beep Codes                  Possible Causes                            Corrective Action
1-2                  No video card detected                 Reseat the video card
1-2-2-3              BIOS ROM checksum error
1-3-1-1              DRAM refresh error                     Reseat the memory modules
1-3-1-3              8742 Keyboard Controller error         Reseat the keyboard connector
1-3-3-1              Memory defective or not present        Reseat the memory modules
1-3-4-1              RAM failure on line xxx                Reseat the memory modules
                     RAM failure on data bits xxx of low
1-3-4-3                                                     Reseat the memory modules
                     byte on memory bus
                     RAM failure on data bits xxx of high
1-4-1-1                                                     Reseat the memory modules
                     byte on memory bus



IBM BIOS beep codes

Below are IBM BIOS Beep codes that can occur. However, because of the wide variety
of models shipping with this BIOS, the beep codes may vary.

Beep Code                                         Description
No Beeps                                          No Power, Loose Card, or Short.
1 Short Beep                                      Normal POST, computer is ok.
2 Short Beep                                      POST error, review screen for error code.
Continuous Beep                                   No Power, Loose Card, or Short.
Repeating Short Beep                              No Power, Loose Card, or Short.
One Long and one Short Beep                       Motherboard issue.
One Long and Two Short Beeps                      Video (Mono/CGA Display Circuitry) issue.
One Long and Three Short Beeps.                   Video (EGA) Display Circuitry.
Three Long Beeps                                  Keyboard / Keyboard card error.
One Beep, Blank or Incorrect Display              Video Display Circuitry.
CPU Installation:
If you have a defective CPU, replacement is easy if you have another identical CPU. Make sure
that you are grounded and insert it (make sure you don’t bend any pins). There is only one way
that a CPU can fit on the motherboard.
If you don’t have the identical speed CPU, you can insert another as long as it has the same
number of pins and an identical BUS (data transfer – usually 66 Mhz, 100 Mhs, 133 Mhz, 200
Mhz) speed to match the motherboard. There is usually a chart on the motherboard with jumper
settings for the various BUS speeds and multipliers (1X, 1.5X, 2X, 2.5X, 3X, …, 15X)

Let’s say you have a 450 Mhz Pentium 3 that needs a new CPU. Problem is – you have an extra
600 Mhz CPU to use. A 450 Mhz CPU has a BUS speed of 100 Mhz. (450 = 100 mhz X 4.5)
You would see the jumpers set for this in the chart on the motherboard (100 Mhz BUS and a 4.5
multiplier). To set the system to use the 600 Mhz CPU, you would have to re-set the jumpers to
the same 100 Mhz BUS, but the multiplier would be 6. Start the machine and you’ll see the new
CPU setting in the first screens that computer shows you at start-up

In older machines (Pentium 1 and Pentium 2), the BUS and multiplier combinations were already
made for you in the chart. You just had to find the correct one – BUT – you have to make sure
that PCI speed was set to 33 Mhz or else your video card, modem, soundcard or network card
might work incorrectly.

Over-clocking a Computer:
Most CPUs have an overhead of speed. A 500 Mhz CPU might have been a 600 Mhz that didn’t
test well in the factory and was “down graded” and marked as such. Many Pentium 2
motherboards have various different BUS speeds that can be used with CPUs to get more speed
from the system. (see chart)

 Example – 300 Mhz (100 Mhz X 3) machine
                                                          BUS (Mhz)   Multiplier   V-Core (Volts)
 Try 105 Mhz X 3 = 315 Mhz and restart the machine.       66          2X           1.65 (newer)
 If the computer POSTs and runs the operating system      75          2.5X         1.7
 - all is well.                                           85          3X           1.75
 Keep using combinations of BUS and multiplier to get     93          3.5X         1.8 (older P2)
 more speed (like 93 X 4 = 325.5, 110 X 3 =330, 85 X      100         4X           1.85
 4 = 340 etc) until the machine won’t work and then       105         4.5X         1.9
 set it back to the last known working configuration.     110         5X           1.95
 Now – add a bit more V-Core voltage (ie 1.8 volts to     115         5.5X         2.0
 1.85) and restart the machine to make sure it works.     120         6X
 Start going up further until the machine stops again.    133         6.5X
 Repeat as above, but set V-Core from 1.85 volts to 1.9               7X
 volts. Try again. Once you get as high as possible,                  7.5X
 run the machine for a while to make sure that it is                  etc
 stable. Over-clocking will cause more heat so good
 CPU cooling is needed. We have taken a 300 Mhz
 Celeron (model 300A with a 66 Mhz BUS) and over-
 clocked it to 540 Mhz. My students like to use this as
 a competition to see how fast they can make a
 machine operate. A good benchmark software is
 SysSoft Sandra. If a CPU doesn’t over-clock well, it
 may not have the speed overhead (a 300 was a 300).

				
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