Beep Codes and POST Diagnostics
Introduction
Most computers nowadays come with some sort of an onboard
diagnostic tool, for troubleshooting hardware faults. It is usually the
motherboard that comes with the diagnostic system, and its most commonly
expressed as a beep code. More sophisticated motherboards have an actual LCD
panel or a Q-Code panel that shows a code in a hexadecimal format.
Whether you have a system that only gives beep codes or if
you have the LCD as well, they can be extremely helpful at diagnosing issues at
POST.
Beep codes
Beep is usually emitted from a small system speaker
connected to the motherboard of your computer. Some motherboards have a speaker
already built in, while others require a separate speaker piece to be attached
on the correct motherboard header.
Depending on the manufacturer of the board and the BIOS,
beep codes can vary significantly amongst all of them, but there are several
things that are pretty universal.
Let's start with the most universal of them all, a single
beep. Single beep is an indication of “Everything OK†message. Typically most
computers simply start up and go into an OS loading screen shortly after a
single beep is heard. While there are rare instances where single beep can be
tied to a specific error, it should be commonly regarded as a successful beep.
In other words, there are no problems.
When problems do occur, system will try to associate a beep
code with the fault that it sees. For example, if the motherboard is aware that
the memory stick in slot #2 is bad, it will give a bad memory beep code.
Usually 3 consecutive beeps will indicate a problem with RAM. Unfortunately,
there are no specific beep codes to tell you exactly which module is broken, so
if you've determined that it is indeed a RAM fault, you would need to test the
system with 1 stick at a time, until you found the defective stick. If you
bought your RAM as a single stick item, then you can replace just that one
stick. Otherwise, if it came as a packaged kit, for example 2x4GB or 2x8GB,
then it's recommended to replace both modules, as kit pairs are usually tested
together. Mixing and matching sticks from different kits can often result in
instability.
Other faults will trigger different types of beep codes, such
as faulty CPU, faulty video card, lack of power to the video card, lack of
power to the board, failed PCI/PCIe device, etc. The codes for these items will
vary based on the manufacturer. Here's a list of common beep codes based on the
BIOS manufacturer:
Award BIOS
1long, 2 short
|
Video adapter error
|
Either video adapter is bad or is not seated
properly. Also, check to ensure the monitor cable is connected
properly.
|
Repeating (endless loop)
|
Memory error
|
Check for improperly seated or missing memory.
|
1long, 3short
|
No video card or bad video RAM
|
Reseat or replace the video card.
|
High frequency beeps while running
|
Overheated CPU
|
Check the CPU fan for proper operation. Check the case for
proper air flow.
|
Repeating High/Low
|
CPU
|
Either the CPU is not seated properly or the CPU is
damaged. May also be due to excess heat. Check the CPU fan or BIOS settings
for proper fan speed.
|
AMI Bios:
1 short
|
DRAM refresh failure
|
The programmable interrupt timer or programmable interrupt
controller has probably failed
|
2 short
|
Memory parity error
|
A memory parity error has occurred in the first 64K of
RAM. The RAM IC is probably bad
|
3 short
|
Base 64K memory failure
|
A memory failure has occurred in the first 64K of
RAM. The RAM IC is probably bad
|
4 short
|
System timer failure
|
The system clock/timer IC has failed or there is a memory
error in the first bank of memory
|
5 short
|
Processor error
|
The system CPU has failed
|
6 short
|
Gate A20 failure
|
The keyboard controller IC has failed, which is not
allowing Gate A20 to switch the processor to protected mode. Replace the
keyboard controller
|
7 short
|
Virtual mode processor exception error
|
The CPU has generated an exception error because of a
fault in the CPU or motherboard circuitry
|
8 short
|
Display memory read/write error
|
The system video adapter is missing or defective
|
9 short
|
ROM checksum error
|
The contents of the system BIOS ROM does not match the
expected checksum value. The BIOS ROM is probably defective and should
be replaced
|
10 short
|
CMOS shutdown register read/write error
|
The shutdown for the CMOS has failed
|
11 short
|
Cache error
|
The L2 cache is faulty
|
1 long, 2 short
|
Failure in video system
|
An error was encountered in the video BIOS ROM, or a
horizontal retrace failure has been encountered
|
1 long, 3 short
|
Memory test failure
|
A fault has been detected in memory above 64KB
|
1 long, 8 short
|
Display test failure
|
The video adapter is either missing or defective
|
2 short
|
POST Failure
|
One of the hardware tests have failed
|
1 long
|
POST has passed all tests
|
|
AMI and Award BIOS modules are some of the most popular ones
in today's boards such as MSI, Gigabyte, Asus and others. If your motherboard
has a different BIOS such as Pheonix or something else, you'll need to consult
the motherboard manual for specific instructions on beep codes.
Couple last things to keep in mind about beep codes. You
have to have a system speaker to hear the codes. It has to be connected to the
board and functioning. If your system doesn't beep at all, try using a
different speaker. Not all faults produce beep codes, especially if the
motherboard isn't even aware that there is a fault. The board can be defective
and not even getting to the diagnostic stage.
Q-Code Reader
Q-Codes are very helpful when diagnosing the POST issues
because they give you an actual code in hexadecimal format, as opposed to just
plain old beeps. Q-code readers are typically pre-installed on motherboards by
the manufacturer, and they usually require having a side panel open so that you
can visually see the code reader. Codes are written in the motherboard manual
along with their explanations and common fixes.
Another benefit to the Q-code readouts is that the system
will cycle through a normal set of codes, until it finally gets frozen on the
last code that gives the issue. Knowing at which point system locks up is also
very beneficial. Some q-codes will get stuck, while others will force the
system to go into a loop and often repeat arriving at the same code. This kind
of information can be useful when you're looking up codes online or in your
motherboard manual.
Couple of last few things to keep in mind about q-codes
-
Make sure your BIOS is always up to the latest
versions, as codes may be added or additional diagnostics algorithms may be
included
-
Also, your BIOS should be updated to support all
the latest hardware. Many people would get failed codes when trying to install
a CPU that was released after the motherboard was available. In this scenario,
BIOS needs to be flashed to the system using the last compatible CPU. If you
received a motherboard with an old BIOS and a CPU that doesn't allow POST, you
would either need to obtain an older CPU or return the board to manufacturer to
get it flashed to latest revision.
-
Visit the manufacturers online download page and
obtain the latest copy of the manual, in case any new errors or codes have been
added.
-
Troubleshoot items one at a time. Do not
introduce too many variables at once, because it may be difficult to determine
the problem.
-
If the code is present upon the very first
startup, ensure that all cables and all devices are properly seated. It's
always best to manually reseat all connections and all components to ensure
best fitment possible.
-
If you've built the system yourself and you're
seeing immediate Q-codes such as 00 or similar faults, that would likely
indicate a DOA motherboard and should be returned back to manufacturer.
We hope that this guide has been informative. If you have
any questions or comments, feel free to post in our help desk section.