Computer Does Not Start and Emits an LED or Beep Code

This document pertains to HP and Compaq Notebook computers.

If your computer makes one or two short beeps before starting but Windows still opens, this is normal and your computer is telling you that BIOS startup was successful. If your computer does not start, listen for beeps and look at the LEDs (Light Emitting Diodes) on the Caps Lock key, the battery, and the AC Adapter, a more serious hardware issue is likely occurring. This support document contains information that can help you learn more about the issue and how to resolve the problem.

Figure 1: Example of blinking LED condition (your computer may look different)

What to do when a LED or beep code occurs

An LED or beep code usually means a basic function was unable to start. A basic function might be 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: Remove dust from cooling areas

If your computer is new and has never been used before, you can skip this step.

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 for startup codes, it is important to remove any dust that may have accumulated.

While wearing eye protection, use canned air to blow out vents, preferrably outdoors.

Figure 2: Blowing dust from air vents

Step 2: Perform a power reset

If your computer does not start, first reset all power to device. Hopefully, the problem is temporary and can be fixed by performing the following steps:

1. Disconnect all peripheral devices such as printers, USB storage devices and media cards.
2. Disconnect the AC power adapter.
3. Remove the battery.
4. Press and hold the power button for at least 15 seconds .
5. Reconnect the AC power adapter (do not connect the battery), and press the Power button .
6. Look for glowing LEDs near caps lock and num lock keys, and listen for sounds of drives and fans turning.
7. If the computer still fails to start and emits lights or beeping sounds, continue to the next section.

Step 4: Match the code to a suspected hardware component and look for possible solutions

Use the LED blink code or beep code to find more information. If your computer emits a an LED blink code, consult the table of boot codes in this support document. If your computer fails to start and emits a beeping noise, use the code to search the Internet for more information. Removing and/or replacing the memory module DIMM and cleaning dust from around the vents can resolve problems related to some beep codes.

Code descriptions

Use the following table to learn about the meaning of a code that your computer may encounter.

Code type	Number of Blinks or Beeps	Component Being Checked	Condition	Possible solution(s)
AC power adapter LED	Constantly on	Power adapter	OK. Power is being supplied.	None. The power adapter is likely not the problem.
AC power adapter LED	Constantly off	Power adapter	Power is not being supplied	Try a different power outlet. Replace power adapter.
AC power adapter LED	Continuous blinking	Power adapter	Insufficient power	Try a different power outlet. Replace power adapter.
Caps Lock/Num Lock	1	CPU	CPU not functional	Reseat replace CPU. Service
Caps Lock/Num Lock	2	BIOS	BIOS corruption failure	Restore BIOS from onboard backup (jumpers) Service
Caps Lock/Num Lock	3	Memory	Memory module error not functional	Reseat memory modules (see next section). Test memory from UEFI or BIOS. Replace bad memory modules. Service
Caps Lock/Num Lock	4	Graphics	Graphics controller not functional	Service
Caps Lock/Num Lock	5	System board	General system board failure	Service
Caps Lock/Num Lock	6	BIOS	BIOS authentication failure	Restore BIOS from onboard backup (jumpers) Service
Beep	Varies	Varies	Varies	Reseat memory modules (see next section). Service For more detail on the exact code, search the Internet for "beep code" and the manufacturer of your BIOS - such as AMI or Award.

Reseating memory modules(s)

If a memory module is loose or is not making good contact with the memory slots, the computer can hang during startup. To reseat the memory module, take the memory module out of the memory slot and then put it back into the slot to get a better connection so that the computer can recognize the memory.

The memory module compartment on most notebooks is located on the bottom of the case, however, on some models, the memory compartment is under the keyboard. See your User Guide for the exact location of memory modules on your notebook.

Testing memory

If the computer can access part of the memory, it may be possible to access the BIOS Setup Utility display and perform a memory self test to identify other memory issues. If the computer cannot boot to the BIOS Utility, try removing and reseating the memory and the hard drive, and then repeat the following steps to perform the memory self test.

1. Plug the AC adapter into the computer.
2. Turn off the computer.
3. Press the Power button to start the computer and repeatedly press the f10 key to enter the BIOS Setup menu.
4. In the BIOS Setup Utility, use the Right Arrow or Left Arrow keys to navigate through the menu selection to locate the Diagnostics .
5. Use the Down Arrow or Up Arrow keys to select Memory Test .
6. Press Enter , and then Yes to perform memory test.
7. After test completes, press f10 key to Save and Exit , and then press Enter key to Exit Saving Changes .

If the test fails, one or more of the memory modules may not be seated properly. Check for and reseat loose memory modules.