Reference number: CH000607

POST troubleshooting steps.

Question:

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.

1. Computer beeps irregularly when the computer is turned on.
2. Computer turns on but does not boot.

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. 

Cause:

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

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

Answer:

Warning: Some of the below steps recommend removing physical parts within the computer. While in the computer it is highly recommend that you be aware of ESD and its potential hazards. Information about ESD and proper grounding techniques are found on our ESD help page.

Note: 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 an power related issue see document CH000312.

Remove new hardware

If any new hardware has been recently added to the computer, remove that hardware to make sure it is not the cause of your issue. If after removing the new hardware your computer works it's likely the computer is either not compatible with the new hardware or a system setting needs to be changed to work with the new hardware device.

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.

Identify beep code

If you are receiving a sequence of beeps see our beep code page for a listing of different beep codes and their explanation and/or your motherboard or computer documentation. These beep codes are meant as a method of quickly identifying what computer component is failing or bad.

Check all fans

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

Check all cables

Verify that all the cables are properly connected at 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 fans.

Disconnect all expansion cards

If the above recommendations still have not resolved the irregular POST attempt to disconnect the Riser board (if applicable) and/or each of the expansion cards. If this resolves the issue or allows the computer to post connect one card at a time until you determine which card is causing the issue.

Disconnect all drives

If you were unable to determine by the beep code what is failing or do not have a beep code disconnect the IDE, SATA, SCSI, or other data cables from the CD-ROM, hard drive, and floppy drive from the Motherboard.

If this resolves your irregular post or you now get an error message attempt to re-connect each device one at a time to determine which device and or cable is causing the issue. In some situations it can also be simply a loose cable connection that causes the issue.

Remove the RAM

If you continue to to receive the same problem with all the above hardware removed attempt to disconnect the RAM from the Motherboard and turn on the computer. If the computer has a different beep code or if your computer was not beeping and is now beeping turn off your computer and try the below suggestions. Making sure to turn off the computer each time you're adding and removing the memory and then turning the computer back on to see if the suggestion resolves the issue.

1. Re-insert the memory into the same slot.
2. If you have more than one stick of memory remove all but one stick of memory, try rotating through each stick.
3. Try one stick of memory in each slot.

If you're able to get the computer to boot with one or more of the sticks of memory it's likely you're dealing with some bad memory. Try to identify which stick of memory is bad and replace it.

If you're able to get memory to work in one slot but not another slot. You're motherboard is defective you can either workaround the issue by running the memory in a different slot or replace the motherboard.

Power cycle the computer

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

This should only be used as a temporary workaround if you're able to get this to work. Often this is good for users who may have not done a backup and need to get the computer up one more time to copy files before starting to replace hardware.

Disconnect and reconnect the CPU

For users who are more comfortable working with the inside of their computer or who have built their computer one last recommendation before assuming hardware is bad is to reseat the CPU by removing it and putting it back into the computer.

Bad motherboard, CPU, RAM, and/or power supply

If after doing all of the above recommendations you continue to have the same issue unfortunately it is likely that you have bad Motherboard, CPU, and or RAM. The next step would be either to replace these components and/or have the computer serviced. If you plan on doing the repairs yourself or you are a repair shop it is suggested that you replace the Motherboard first, RAM, CPU, and then power supply in that order and/or try swappable parts from other computers.

• See our buying help page for tips and information about buying computer hardware. 
• See document CHADD for additional information about installing new hardware into the computer.