3 POST BIOS EDUCATION COMPUTER SYSTEM SERVICING.pptx

POWER ON SELF-TEST
(POST) / BEEP CODES

OBJECTIVES
1. Explain the importance of Power On Self-Test
(POST);
2. Inspect Power On Self-Test (POST) activity of the
computer; and
3. Recognize beep codes during Power On Self-Test
(POST).

The information that you see in the
desktop monitor is the result of the
Power On Self-Test (POST) upon
opening the computer.

Power On Self-Test (POST)
◦is a process performed by firmware or
software routines immediately after a
computer is powered on. The POST
process may also set the initial state of
the device from firmware.

Power On Self-Test (POST)
◦The POST routines are part of a device's
pre-boot sequence; if they complete
successfully, the bootstrap loader code
is invoked to load an operating system.

◦Programs stored on ROM chips are
known as firmware
◦Programs stored on erasable media are
called software

◦Firmware is software that's embedded
in a piece of hardware. It is simply
as "software for hardware."

◦Power On Self-Test (POST) checks
computer hardware, like Random
Access Memory(RAM), hard drive, CD-
ROM drive, keyboard, etc., to make sure
all are working correctly.

◦If all hardware pasts the POST, the
computer will continue the boot up
process and may generate a single beep
sound as well. If POST is unsuccessful, it
generates a beep code to indicate the error
encountered and the computer will not
boot up.

◦All POST errors are relating to hardware
issues with one of the components in
the computer.

◦Beep codes may vary depending on
manufacturer’s BIOS chip that is used
by the motherboard.

AMI BIOS Beep Codes (American
Megatrends, Inc.)

Remove new hardware
If any new hardware was recently added to the computer, remove
that hardware to make sure it is not causing your issue. If your
computer works after removing the new hardware, it can mean a
few things. Either the new hardware is not compatible with your
computer, a system setting needs to be changed, or the new
hardware is defective.

Remove any disks or USB devices
Remove any disks, CDs, or DVDs that are in the computer. If any USB
devices (iPods, drives, phones, etc.) are connected, disconnect all of
them as well. Reboot the computer and see if anything changes..

Disconnect external devices
Remove everything from the back of the computer, except the power
cable. Turn on the computer and see if it beeps normally. If the
computer has never beeped, keep the monitor or display connected
to see if any change occurs.

Reconnect and check power cords
If the computer is not getting enough power or the power is getting
interrupted, the computer can encounter problems. Disconnect your
power cables from any power strip or UPS (uninterruptible power
supply) and connect the computer directly to a known good wall
outlet.

Identify beep code
If you are receiving a sequence of beeps, you can also check your
motherboard or computer documentation for information on the
beep codes. These beep codes are meant to help identify which
computer component is failing or bad. If your beep code is not listed,
continue troubleshooting.

Check all fans
Make sure all fans are running on the computer. If a fan has failed
(especially the heat sink fan for the CPU), your computer could be
overheating or detecting the fan failure, causing the computer not to
boot.

Check all cables
Verify all the cables are securely connected to the computer and that
there are no loose cables by firmly pressing in each cable.
All disk drives should have a data cable and power cable connected
to them.
Your power supply should have at least one cable going to the
motherboard.
Many motherboards may also have additional cables connected to
them to supply power to the fan

Disconnect all expansion cards
If the above recommendations still have not resolved the
irregular POST, disconnect the riser board (if applicable) and each of
the expansion cards. If this fixes the problem or allows the computer
to POST, connect one card at a time until you determine which card
is causing the problem.

Disconnect all drives
If you do not hear a beep code, power off the computer. Then,
disconnect any IDE, SATA, SCSI, or other data cables from the
motherboard. When they are disconnected, try booting the
computer again. If this resolves your irregular POST or generates
error messages, reconnect each device until you determine which
device or cable is causing the issue. In some situations, it can also be
a loose cable connection that causes the issue.

Remove the RAM
If you continue to experience the same problem with all the above
hardware removed, remove the RAM from the motherboard and
turn on the computer. Make sure to turn off the computer before
adding and removing the memory and then turning it back on to see
if the suggestion resolves the issue.

Remove the RAM
1. Re-insert the memory into the same slot.
2. If you have more than one stick of memory, try to stick them in
each slot .
If you can get the computer to boot with one or more of the sticks of
memory installed, you are likely dealing with some bad memory. Try
to identify which stick of memory is bad and replace it.

Power Cycle the Computer
In some situations, a computer may have power related issues often
caused by either the power supply or the motherboard. To help
determine if this is the issue, try turning the computer on, off, and
back on as fast as possible, making sure the computer power light
goes on and off. In some situations, you may be able to temporarily
get the computer to boot.

Power Cycle the Computer
Warning:
Try this method only as a temporary workaround or as a last resort
to get any valuable information from the computer.

Disconnect and reconnect the CPU
For users who're more comfortable working inside their computer,
reseat the CPU by removing it and re-inserting it into the socket. You
should also apply a fresh layer of thermal compound between the
CPU and the heat sink.

Loose BIOS chip
Loose over time due to heat expansion causes the computer to give
an irregular POST. Gently press down on the BIOS chip to make sure
it has not become loose.

Bad motherboard, CPU, RAM, or power
supply
If, after trying all of the above recommendations you still have an
issue, you likely have a bad motherboard, power supply, CPU, or
RAM stick.
Note: If you plan to repair it by yourself, replace or swap in parts
from another computer that is known to work. Replace the
motherboard first, then the RAM, the CPU, and finally, the power
supply.

Remember
POST has an important role that determines the condition of both
hardware and software components of the computer. With the help
of the beep codes we easily determine which components
are needed to be fix and give some attention.

Objectives
• Discuss how to configure the BIOS;
• Perform BIOS configuration based on the given procedures; and
• Carry out work in accordance with hardware requirements.

Basic Input/Output System (BIOS) is a ROM
chip found on motherboards that allows you to
access and set up your computer system.

3 POST BIOS EDUCATION COMPUTER SYSTEM SERVICING.pptx

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3 POST BIOS EDUCATION COMPUTER SYSTEM SERVICING.pptx