Troubleshooting in Build: POST

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POST Troubleshooting

Getting a computer to POST (Power On Self Test) can be a challenging experience. Some computers will have the "Did not POST" checkbox marked on the Green Light Sticker on the system, and sometimes, there's no advance warning. Either way, there are some steps you can take in order to troubleshoot a non-POSTing system, and we've got a few suggestions below:


Notes and Detailed Instructions

Ensure All Hardware Is Connected Properly

Now, this may seem really rudimentary, but making sure a system is properly put together before trying to POST a computer is definitely worth reviewing. Make sure the following is done on any system:

  • Make sure the power cord is properly plugged into the system, and properly plugged into a socket that is not hooked up to an "off" power supply.
  • Ensure that the on-board video/video card is securely connected to the VGA/DVI connector, and that the cable is also connected to the monitor properly.
  • Look over the power supply; if there is a power switch on the back, make sure it is flipped on to the "I" and not the "O" position. Next, make certain the power supply harnesses are connected properly to the motherboard. If nothing seems connected and you're unsure of where to plug in the loose harnesses, ask a neighbor or a build instructor for guidance.
  • Ensure that any CD-ROM/DVD/Floppy disk drives are NOT connected to the Motherboard at this time. Simplify and...!
  • Lastly, look over the motherboard really well to see if there are any blown caps!
No POST, and the computer is beeping at me!

If when you power on the system, and you hear a series of beeps...that COULD mean your system is pleading with you to give it some memory, and the right memory. It could also mean that its trying to tell you something else. First, try and distinctly identify exactly what series of beeps your system is giving you and consult Beep Codes to find the corresponding beep sequence. If it could be pointing to an issue with your memory, look at the DDR slots on the motherboard and start with determining if its DDR1 or DDR2. Then try putting in the slowest speed memory and begin working your way up. Restart the system each time and see if any stick does the trick. If not, try different combinations in various DDR slots to see if there is any life in the system. If all this fails, grab a Build Instructor, fill him/her in on what you've done, and see if they have any suggestions for moving forward.

"When I turn on the system... No fans come on... nothing seems to happen!

This could indicate that you have a bad power supply. Simply go to where the battery testers are and you should see a power supply tester. If you need assistance on how to test the power supply, reach out to a neighbor or build instructor. If the power supply is bad, replace it with something that has a similar harness connection (ie 24/20 pin cable/Dell/ATX/etc.) and wattage. These can be found in Pre-Build on the left just before you walk into the warehouse. If you're power supply passes the test, you may have a bad processor. Notify a Build Instructor and work with him/her in order to get the correct information on what processor the system takes, and the build instructor will look in Free Geeks inventory to see if there is one that is tested and available.

To replace a processor, start by removing the fan and heat sink, swapping the old processor for the new one, and placing a small dot of thermal paste (located next to where the power supply tester is) on to the middle of the processor's shield. Put the heat sink and fan back in place and try to power on the system. If it still doesn't power on, or if there is no replacement processor, ask a build instructor if the system should be "Rejected" and they can help you begin that process.

I've got fans going, but its still an empty stage (i.e., no POST showing on the monitor)

If the system seems to light up, the fans are moving, and the system isn't beeping at you, try installing a video card (AGP or PCIe) and take the VGA/DVI cable that was connected to the onboard or current video card and connect it to the new card. Boot up the system on the new card and see if this helps.

Remember the Beep Codes mentioned above? Sometimes, they can be used to determine whether or not your motherboard is healthy! If you can't get any video but everything seems to power on fine, try removing all the device connections (IDE, SATA, etc) and taking out all of the RAM. If the manufacturer included Beep Codes into their system, then it should send out its code for Missing/Bad memory. This can eliminate the possibility of a bad a mobo, and reduce the number of steps you might need to take to troubleshoot the system. Remember that this doesn't apply to all systems! However, it can be particular useful when you're working on Dell machines, for example.