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Computer does not start and the LEDs blink or the computer beeps

This document pertains to HP and Compaq Notebook computers.
If your computer makes one or two short beeps while starting, and Windows still opens, the computer is indicating normal BIOS startup was successful. If your computer does not start, a more serious hardware issue is likely occurring. Listen for beeps and look at the LEDs (light emitting diodes) near the Num Lock and Caps Lock keys, the battery, and the AC adapter to help determine troubleshooting steps. This support document contains information that can help you learn more about the issue and how to resolve the problem.
Figure : Example of blinking LED condition (your computer may look different)
 Image of a notebook computer with lid open and showing animated lights blinking on and off.
First steps when a notebook LED or beep code occurs
An LED or beep code usually means a basic function is unable to start. A basic function might include reading memory, displaying video, or being able to send information to a hard drive. The most common problems that cause LED and beep codes are memory and heat-related failures caused by a build-up of dust in critical cooling areas.
Use the following steps when your computer emits an LED code or beep code:
Step 1: Performing a hard reset or forced reset on a notebook computer
Before you begin, turn the computer over and look for a battery compartment door. If there is no battery compartment, use the steps in the sealed or non-removable battery section.
Step 2: Removing dust from the cooling areas in a notebook
Over time, dust can collect in the cooling vents of your computer. Too much dust can block airflow, causing sensitive components to overheat and fail. Before troubleshooting startup codes, it is important to remove any dust that may have accumulated.
While wearing eye protection, use canned air to blow out vents, preferably outdoors.
Figure : Blowing dust from air vents
Air cleaner nozzle over side vent
After cleaning the computer's air vents, restart the computer.
If the computer starts normally, you are done. Otherwise, proceed to the next step.
Step 3: Writing down the LED or beep code
Use the following steps to write down the LED or beep codes onto a piece of paper.
  1. Press the Power button to turn on the computer.
  2. Your computer's power socket or power adapter may have an LED. If it has an LED, look at the light next to the power socket or the light on the AC power adapter and note its condition: off, blinking, or constantly on.
  3. Look at the indicator lights near the Caps Lock and Num Lock keys and note their condition. If the lights blink, count the number of times they blink between pauses.
     note:
    After a sequence of blinks or beeps, there is a pause for a few seconds, and the sequence is repeated (usually 3 or 4 times). The blink sequence can be repeated by pressing the Power button.
  4. Listen to your computer for any loud beeping noises. If your computer makes a beeping noise, note the type and number of beeps between pauses. For example: two long beeps followed by one short beep.
  5. On a piece of paper, write down what you have noted to remember the LED or beep code. Then proceed to the next section.
Notebook battery power LED blinks
The Battery power LED indicates the condition of the power supply. When starting the computer, or when the computer is in operation, use the chart to identify the power condition.
The battery power LED is generally a lightning bolt icon. (If the notebook does not have the lightning bolt battery power LED, consult the product manual.)
Battery Power LED
Component Tested
Error Condition
Battery power LED off, and Caps Lock/Num Lock off
Battery or AC Adapter
AC adapter not connected or failure
Battery low charge or failure
Battery power LED blinking
Battery
Insufficient charge on the battery
Refer to one of the following sections for more information about the battery power status:
LEDs near Caps Lock and Number Lock keys blink when starting the notebook
The notebook diagnostic utilities use the LEDs near the Num Lock and Caps Lock keys to blink a series of error codes ("blink codes"). At the end of the series the blinking stops. Until the error is resolved, the pattern of blinks will occur any time an attempt is made to start the computer.
The LED lights near the Caps Lock and Num Lock keys will blink if an error is detected during the startup process. The LEDs will blink a number of times in a sequence and then stop. The number of blinks in the sequence indicates what component caused an error when it was being tested during start up.
If the LEDs stop blinking and the computer does not start, you can press the Power button again to repeat the tests. After you count the number of blinks, use the chart to identify the error condition, and then see the corresponding section for that error condition below for troubleshooting steps.
 note:
Knowing the number of blinks is helpful when you contact an HP support agent for technical help.
Caps Lock/Num Lock LED
Component tested
Error condition
LEDs blink 1 time
CPU
CPU not functional
LEDs blink 2 times
BIOS
BIOS corruption failure
LEDs blink 3 times
Memory
Module error not functional
LEDs blink 4 times
Graphics
Graphics controller not functional
LEDs blink 5 times
System board
General system board failure
LEDs blink 6 times
BIOS
BIOS authentication failure
Computer makes beeping sounds
The most common cause of a computer beeping upon startup is a loose or bad memory module. Reseat the memory modules to resolve problems with the computer beeping. If this does not resolve the issue, contact HP for assistance.
Contacting HP Support
If you cannot find a troubleshooting solution, contact HP support for further assistance or to have the computer serviced.

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