What To Do When Your Computer Won’t Start, Turn On, or Power Up?
This is a very long In Depth Video Tutorial that I would advise any “newbie” Tech to watch from beginning to end. It provides a wealth of information that is one of the first things us Veterans Techs would walk through immediately with in the first two to three minutes of diagnosing a power on or start up problem common to many Personal Computers.
This document was orginally published courtesy of: Hewlett Packard at:
http://h10025.www1.hp.com/ewfrf/wc/document?docname=bph07107&cc=us&dlc=en&lc=en#N331
And is published with the intention of helping Compaq and Hewlett Packard customers..
Computer Does Not Start and Emits an LED or Beep Code
Feedback
This document pertains to HP and Compaq Desktop computers.
If your computer makes one or two short beeps before starting, this is normal and your computer is telling you that BIOS startup was successful. If your computer beeps and does not start, 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.
What to do when beep codes occur
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 or the end of a vacuum cleaner to remove dust from vents, preferrably outdoors.
Figure 1: Vacumming 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:
- Disconnect all peripheral devices such as printers, USB storage devices and media cards.
- Disconnect the power cord from the computer.
- Press and hold the power button for at least 15 seconds until the power LED on the power supply is off.
- Reconnect the power cord, and press the Power button .
- Listen for sounds of drives and fans turning.
- If the computer still fails to start and emits beeping sounds, continue to the next section.
Step 3: Write down the LED condition or beep code
Use the following steps to write down the error conditions onto a piece of paper.
- Press the power button to turn on the computer.
- Look at the Power button on your computer’s case and note its condition. If the light blinks, count the number of times it blinks between pauses.
- 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.
- On a piece of paper, write down what you have noted to remember the error when doing the next steps.
NOTE:Boot or post codes have changed over time. Earlier computers use a series of beeps. The number and type of beeps depend on the age of the computer as well as the manufacturer of the motherboard and BIOS. With the development of the Extensible Firmware Interface (EFI) environment, many HP Pavilion and Compaq Presario computers built in 2011 or later can use blinking LEDS to identify hardware component reporting an error during startup. These codes are not valid for earlier models.
Step 4: Match the code to a suspected hardware component
Consult the Beep code descriptions section in this support document to try and find the component that is having a problem. You can use this information in the next step when performing the troubleshooting. Or, in the event your computer requires service, you can use this code and information when talking with the service personell.
Step 5: Isolate and fix the problem
HP recommends that these steps be performed only by someone with experience in working on computer hardware. Incorrectly handling sensitive internal components can further damage the computer and can introduce the risk of personal injury.
WARNING:Using the correct environment for working on computers (ESD precautions and tools), use the following steps to isolate and fix the problem:
- Turn on the computer.
- Check the system fan and power cable:
- Turn off the computer by holding the power button for five seconds.
- Disconnect the power cord and then disconnect all external cords from the computer.
- Remove the side panel to open the computer.
- If the system fan was not spinning, make sure the system fan power cable is connected to the correct pins on the motherboard. Replace the fan if it was making excessive noise or was not spinning.If you had to plug in or replace the fan, replace the side panel, plug in the power cord and turn on the computer. If the beeps continue, continue to the next step.
- Disconnect the power cord and remove the side panel and perform each of the following tasks, in order, until the beeping stops:Before starting each task, unplug the power cord and remove the side panel.After completing a task, replace the side panel, connect the power cord, turn on the computer, and listen for a beep code.NOTE:If removing or disconnecting a hardware component prevents the beep code, that component is probably causing the problem. However, a failed motherboard might produce beep codes associated with a component other than the motherboard.Clean internal cooling components that have become clogged with dust. If beeping continues, continue to the next step.Remove a memory module.If the computer stops beeping, the memory module might be bad, is the wrong type of memory for the motherboard, or was not fully seated or connected. Reinsert the memory into the socket to see if a connection was the problem; otherwise replace the module.Remove each memory module, replacing the one that was previously removed. If beeping continues after checking all the memory modules, continue to the next step.If the computer has a graphics adapter, remove it.If the beep code changes or continues with the same beep pattern after removing the graphics adapter, the adapter might still be good. Reseat the graphics adapter into its socket and continue to the next step.If the beep code goes away, the graphics adapter might be bad. Try reseating the graphics adapter, making sure it is fully locked into the connector on the motherboard. If problems continue, replace the adapter.Remove a PCI card.If the beep code goes away, the card might be bad. Try reseating the card into its connector on the motherboard. If problems continue, replace the card.Remove each PCI card, replacing the one that was previously removed. After checking all cards, if beeping continues, continue to the next step.Disconnect each hard drive and CD or DVD drive cable (IDE and ATA) from the motherboard socket. Disconnect each drive cable, replacing the one that was previously disconnected, until all cables have been checked.If the beep code goes away, the cable or socket is probably bad. Look for bent pins inside the IDE socket on the motherboard and straighten any bent pins. Try reseating the cables into the connectors. If problems continue, the drive itself might be bad and might need replacing.After checking all connections, if beeping continues, continue to the next step.At this point, the problem is probably the motherboard or processor. Make sure any jumpers on the motherboard have not fallen off their pins and into the case. Make sure jumpers are set correctly. Otherwise, have the computer serviced by HP or by a qualified service center.
Beep and LED code descriptions
Beep code tables are provided in the following sections of this document to help you isolate and understand the issue. This might reduce the time required to solve the problem. Read one of the following sections.
Flashing light codes
On some computers, the motherboard can flash or change the color of lights on the outside of the case, such as the power button LED and the hard drive activity LED. For computers that support this technology, lights blink and and provide a beep to indicate a failure condition.
| LED and beep condition | Description |
|---|---|
| Power button LED blinks 4 times with 4 beeps | Power Supply |
| Power button LED blinks 5 times with 5 beeps | Memory |
| Power button LED blinks 6 times with 6 beeps | Video Card or Graphics |
| Power button LED blinks 7 times with 7 beeps | Motherboard or System Board failure |
| Power button LED blinks 8 times with 8 beeps | BIOS or CMOS problem (ROM) |
Example of LED conditions: click a menu item to view the condition
Beep codes common to HP and Compaq Desktop PCs
The following beep codes are common to many HP and Compaq desktop computers. Use these codes before referring to the other codes when they occur.
| Beeps | Description |
|---|---|
| 1 short beep and 1 long beep | Memory problem |
| 2 short beeps and 1 long beep (repeats 5 times) | Unable to initialize video or video card required but not installed |
| 3 short beeps and 1 long beep | CPU configuration error or CPU type is not compatible |
The following beep codes are common to many HP and Compaq desktop computers that can occurwhile restoring, flashing or updating the BIOS :
| Beeps | Description |
|---|---|
| 1 short beep | Legacy floppy drive or CD/DVD drive not detected |
| 2 short beeps | Floppy diskette or compact disc not detected |
| 3 short beeps | Unable to start flashing (such as when missing a utility or BIOS image) |
| 4 short beeps | Flashing failed (checksum error, corrupted image, etc.) |
| 5 short beeps | BIOS recovery successful |
Beep codes for American Megatrends, Inc (AMI) BIOS
The following AMI beep codes can occur when there is a problem during the attempt of a normal system startup. You can use these codes to help troubleshoot issues related to system startup. When troubleshooting further, please refer to the section What to do when beep codes occur .
NOTE:The following codes can vary depending on BIOS version.
| Beeps | Description |
|---|---|
| 1 | Memory timing failure |
| 2 | Memory parity error |
| 3 | Memory read or write failure |
| 4, 5, 6, 7 | Fatal errors related to the operation of critical motherboard components – such as the CPU. |
| 8 | Video memory |
The following table lists AMI beep codes that can occur when attempting to flash or recover the BIOS. You can use these codes to help troubleshoot problems related to system startup or flashing BIOS memory (such as in BIOS upgrades).
NOTE:The following codes can vary depending on BIOS version.
| Number of beeps | Post code |
|---|---|
| 1 | No media detected |
| 2 | ROM file not found in root directory |
| 3 | Insert next media volume |
| 4 | Flash Programming successful |
| 5 | Failure while reading file |
| 7 | Flash EPROM not detected |
| 10 | Failure while erasing flash memory |
| 11 | Flash program error |
| 12 | Problem with ROM file size |
| 13 | ROM image does not match BIOS requirements |
Beep codes for Award BIOS
Most Award post codes are displayed to screen. If a beep code occurs the problem is likely occurring before the system can display video (check the video card or memory).
NOTE:The following codes can vary depending on BIOS version.
| Beeps | Description |
|---|---|
| 1 short beep | POST process completed successfully – normal startup |
| 1 long beep followed by 2 or 3 short beeps | Unable to initialize video (to display the post code) |
| Continuous beeping without pause | Serious system related issue such as CPU overheating |
| Other beep conditions | Memory errors. |
Beep codes for Phoenix BIOS (for older PCs)
You can use these codes to help troubleshoot issues related to system startup or flashing BIOS memory (such as in BIOS upgrades). When troubleshooting further, please refer to the sectionWhat to do when beep codes occur .
Four series of beeps indicate a fatal error; that is, a problem exists which prevents the computer from starting. For example, there might be two beeps, a short pause, one beep, a short pause, one beep, a short pause, and then three beeps; this is represented as 2-1-1-3 in the chart below.
NOTE:The following codes can vary depending on BIOS version.
| Beeps | Post Code | Description of failure |
| One short beep | 0 | POST process completed successfully – normal startup |
| 1-1-1-3 | 02h | Verify real mode |
| 1-1-2-1 | 04h | Get CPU type |
| 1-1-2-3 | 06h | Initialize system hardware |
| 1-1-3-1 | 08h | Initialize chipset registers with initial POST values |
| 1-1-3-2 | 09h | Set in POST flag |
| 1-1-3-3 | 0Ah | Initialize CPU registers |
| 1-1-4-1 | 0Ch | Initialize cache to initial POST values |
| 1-1-4-3 | 0Eh | Initialize I/O |
| 1-2-1-1 | 10h | Initialize Power Management |
| 1-2-1-2 | 11h | Load alternate registers with initial POST values |
| 1-2-1-3 | 12h | Jump to UserPatch0 |
| 1-2-2-1 | 14h | Initialize keyboard controller |
| 1-2-2-3 | 16h | BIOS ROM checksum |
| 1-2-3-1 | 18h | 8254 timer initialization |
| 1-2-3-3 | 1Ah | 8237 DMA controller initialization |
| 1-2-4-1 | 1Ch | Reset Programmable Interrupt Controller |
| 1-3-1-1 | 20h | Test DRAM refresh |
| 1-3-1-3 | 22h | Test 8742 Keyboard Controller |
| 1-3-2-1 | 24h | Set ES segment register to 4 GB |
| 1-3-3-1 | 28h | Autosize DRAM |
| 1-3-3-3 | 2Ah | Clear 512K base RAM |
| 1-3-4-1 | 2Ch | Test 512 base address lines |
| 1-3-4-3 | 2Eh | Test 512K base memory |
| 1-4-1-3 | 32h | Test CPU bus-clock frequency |
| 1-4-2-1 | 34h | CMOS RAM read/write failure |
| 1-4-2-4 | 37h | Reinitialize the chipset |
| 1-4-3-1 | 38h | Shadow system BIOS ROM |
| 1-4-3-2 | 39h | Reinitialize the cache |
| 1-4-3-3 | 3Ah | Autosize cache |
| 1-4-4-1 | 3Ch | Configure advanced chipset registers |
| 1-4-4-2 | 3Dh | Load alternate registers with CMOS values |
| 2-1-1-1 | 40h | Set Initial CPU speed |
| 2-1-1-3 | 42hs | Initialize interrupt vector |
| 2-1-2-1 | 44h | Initialize BIOS interrupts |
| 2-1-2-3 | 46h | Check ROM copyright notice |
| 2-1-2-4 | 47h | Initialize manager for PCI Options ROMs |
| 2-1-3-1 | 48h | Check video configuration against CMOS |
| 2-1-3-2 | 49h | Initialize PCI bus and devices |
| 2-1-3-3 | 4Ah | Initialize all video adapters in system |
| 2-1-4-1 | 4Ch | Shadow video BIOS ROM |
| 2-1-4-3 | 4Eh | Display copyright notice |
| 2-2-1-1 | 50h | Display CPU type and speed |
| 2-2-1-3 | 52h | Test keyboard |
| 2-2-2-1 | 54h | Set key click if enabled |
| 2-2-2-3 | 56h | Enable keyboard |
| 2-2-3-1 | 58h | Test for unexpected interrupts |
| 2-2-3-3 | 5Ah | Display prompt “Press F2 to enter SETUP” |
| 2-2-4-1 | 5Ch | Test RAM between 512 and 640k |
| 2-3-1-1 | 60h | Test expanded memory |
| 2-3-1-3 | 62h | Test extended memory address lines |
| 2-3-2-1 | 64h | Jump to UserPatch1 |
| 2-3-2-3 | 66h | Configure advanced cache registers |
| 2-3-3-1 | 68h | Enable external and CPU caches |
| 2-3-3-2 | 69h | Initialize SMI handler |
| 2-3-3-3 | 6Ah | Display external cache size |
| 2-3-4-1 | 6Ch | Display shadow message |
| 2-3-4-3 | 6Eh | Display non-disposable segments |
| 2-4-1-1 | 70h | Display error messages |
| 2-4-1-3 | 72h | Check for configuration errors |
| 2-4-2-1 | 74h | Test real-time clock |
| 2-4-2-3 | 76h | Check for keyboard errors |
| 2-4-4-1 | 7Ch | Set up hardware interrupts vectors |
| 2-4-4-3 | 7Eh | Test coprocessor if present |
| 3-1-1-1 | 80h | Disable onboard I/O ports |
| 3-1-1-3 | 82h | Detect and install external RS232 ports |
| 3-1-2-1 | 84h | Detect and install external parallel ports |
| 3-1-2-3 | 86h | Re-initialize onboard I/O ports |
| 3-1-3-1 | 88h | Initialize BIOS data area |
| 3-1-3-3 | 8Ah | Initialize extended BIOS data area |
| 3-1-4-1 | 8Ch | Initialize floppy controller |
| 3-2-1-1 | 90h | Initialize hard-disk controller |
| 3-2-1-2 | 91h | Initialize local-bus hard-disk controller |
| 3-2-1-3 | 92h | Jump to UserPatch2 |
| 3-2-2-1 | 94h | Disable A20 address line |
| 3-2-2-3 | 96h | Clear huge ES segment register |
| 3-2-3-1 | 98h | Search for option ROMs |
| 3-2-3-3 | 9Ah | Shadow option ROMs |
| 3-2-4-1 | 9Ch | Set up Power Management |
| 3-2-4-3 | 9Eh | Enable hardware interrupts |
| 3-3-1-1 | A0h | Set time of day |
| 3-3-1-3 | A2h | Check key lock |
| 3-3-3-1 | A8h | Erase F2 prompt |
| 3-3-3-3 | Aah | Scan for F2 key stroke |
| 3-3-4-1 | AChP | Enter SETUP |
| 3-3-4-3 | Aeh | Clear in-POST flag |
| 3-4-1-1 | B0h | Check for errors |
| 3-4-1-3 | B2h | POST done–prepare to boot operating system |
| 3-4-2-1 | B4h | One beep |
| 3-4-2-3 | B6h | Check password (optional) |
| 3-4-3-1 | B8h | Clear global descriptor table |
| 3-4-4-1 | BCh | Clear parity checkers |
| 3-4-4-3 | Beh | Clear screen (optional) |
| 3-4-4-4 | BFh | Check virus and backup reminders |
| 4-1-1-1 | C0h | Try to boot with INT 19 |
| 4-2-1-1 | D0h | Interrupt handler error |
| 4-2-1-3 | D2h | Unknown interrupt error |
| 4-2-2-1 | D4h | Pending interrupt error |
| 4-2-2-3 | D6h | Initialize option ROM error |
| 4-2-3-1 | D8h | Shutdown error |
| 4-2-3-3 | Dah | Extended Block Move |
| 4-2-4-1 | DCh | Shutdown error |
| 4-2-4-3 | Deh | Keyboard Controller Failure |
| 4-3-1-3 | E2h | Initialize the chipset |
| 4-3-1-4 | E3h | Initialize refresh counter |
| 4-3-2-1 | E4h | Check for Forced Flash |
| 4-3-2-2 | E5h | Check HW status of ROM |
| 4-3-2-3 | E6h | BIOS ROM is OK |
| 4-3-2-4 | E7h | Do a complete RAM test |
| 4-3-3-1 | E8h | Do OEM initialization |
| 4-3-3-2 | E9h | Initialize interrupt controller |
| 4-3-3-3 | Eah | Read in bootstrap code |
| 4-3-3-4 | Ebh | Initialize all vectors |
| 4-3-4-1 | Ech | Boot the Flash program |
| 4-3-4-2 | Edh | Initialize the boot device |
| 4-3-4-3 | Eeh | Boot code was read OK |
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.
- Plug the AC adapter into the computer.
- Turn off the computer.
- Press the Power button to start the computer and repeatedly press the f10 key to enter the BIOS Setup menu.
- In the BIOS Setup Utility, use the Right Arrow or Left Arrow keys to navigate through the menu selection to locate the Diagnostics .
- Use the Down Arrow or Up Arrow keys to select Memory Test .
- Press Enter , and then Yes to perform memory test.
- 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.
Finding service
Many of the problems associated with LED or beep codes require service or parts replacement. To find an HP authorized service provide, go to www.hp.com/go/support .
