top of page



The Steps Of A POST When Booting Up Any Computer:


Each time the computer boots up the computer must past the POST. Below is the common steps a POST performs each time your computer starts.


    Test the power supply to ensure that it is turned on and that it releases its reset signal.
    CPU must exit the reset status mode and thereafter be able to execute instructions.
    BIOS checksum must be valid, meaning that it must be readable.
    CMOS checksum must be valid, meaning that it must be readable.
    CPU must be able to read all forms of memory such as the memory controller, memory bus, and memory module.
    The first 64KB of memory must be operational and have the capability to be read and written to and from, and capable of


    the POST code.
    I/O bus / controller must be accessible.
    I/O bus must be able to write / read from the video subsystem and be able to read all video RAM


If the computer does not pass any of the above tests, your computer will receive an irregular POST.

An irregular POST is a beep code that is different from the standard one or two beeps.

This could be either no beeps at all or a combination of different beeps indicating what is causing the computer not to past the POST.


If you're getting a beep code, underneith is a listing of each of the major manufacturers beep codes and what they each mean.







POST troubleshooting steps.
Additional information:

This document is intended to help users who are experiencing issues with the POST and may have any of the below symptoms.

    Computer beeps irregularly when the computer is turned on.
    Computer turns on but does not boot.
    Turn on the computer but doesn't do anything.
    Computer reboots every few seconds.


Note: Not all computers have beep codes, some of the newer computers have LED's that light up that indicate the error or have

            a sound file to indicate the error.

   This issue can be caused by any of the below situations.

    New hardware conflicting with old hardware.
    Bad or failing hardware device.
    Connections not connected or connected properly.
    Recent electrical storm that caused a surge that damaged computer.
    Other hardware issue.



Make sure your computer is turning on, if you press the power button and nothing happens (no lights, no sound, no fans, etc.) then this issue is not a NO POST but is a power related issue.


T-ComTech Computer Boot Up Help

bottom of page