Tutorial: NO POST / Power General troublshooting


Techspot old timer.....
You just built a computer, or the one you have suddenly won't boot up.... what you have now is a P.O.S.T. Failure. (Power On Self Test).
This document is intended to help users who are experiencing issues with 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.

A POST failure can be caused by any of the following situations.
1.New hardware conflicting with old hardware
2.Bad or failing hardware device.
3.Other hardware issue. (electrical shorts or incompatibilities.)

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 electro-static discharge and its potential hazards. ALWAYS ground yourself and your equipment. Ensure your computer is unplugged!

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.

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.

1.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 also connect a monitor to the computer to see if any change occurs.

2.Check the stand-offs (the metal or plastic insulators) that keep your motherboard off and away from the case or housing. Ensure they are not grounding or shorting the motherboard out. If they are metal, ensure that the cardboard insulators are present. Ensure the motherboard is not grounding out to the case also at any other point.

3.If you are receiving a sequence of beeps consult your motherboard manual or the motherboard manufacturer's website for a listing of different beep codes and their explanation. These beep codes are meant as a method of quickly identifying what computer component is failing or bad.

4.Check to make sure power cables are not grounding or shorting to the case or other components. Ensure all ends are connected properly, securely, and snugly.

5.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.

6.If you were unable to determine by the beep code what is failing or do not have a beep code disconnect the IDE cables from the CD-ROM, Hard Drive, and Floppy drive from the Motherboard. If this resolves your post failure, attempt to connect each device one at a time to determine which device and or cable is causing the issue.

7.If the above recommendations still have not resolved the irregular POST, start disconnecting your expansion riser cards, these are the cards that are not essential to system operation. Break your motherboard down to the bare basics. Disconnect your floppy drive, CD/DVD Rom, and hard drives Your motherboard basics should have just the following: video card, RAM, motherboard and PSU (power supply unit). If this resolves the issue or allows the computer to post connect one card or device at a time until you determine which card or device is causing the issue.

8.If you continue to to receive the same problem with all the above hardware removed attempt to disconnect the CPU and RAM from the Motherboard. Once done insert the CPU and RAM back into the computer to see doing this resolves your issue.

9.Ensure your PSU is of the correct size and power requirements for your system. Many newer motherboards and graphics cards are power intensive. Some newer graphics cards require their own separate power supplies. An underpowered PSU, will also cause system failure. Most new systems will not run well with less than 450W PSUs.

10.If after doing all of the above recommendations you continue to have the same issues unfortunately it is likely that you have bad or incompatible components, in particular RAM. Ensure your RAM is compatible with the motherboard. Many newer motherboards are very specific about what RAM sticks they will accept. Don't mix and match RAM speeds, type, or size.

11.If you have determined your components are compatible, then you have faulty hardware. The next step would be to test each component separately. You will need to find a working motherboard to test RAM with a diagnostic program like Memtest 86+. A faulty motherboard will need to be simply replaced. A bad PSU can only be replaced. Don't attempt to repair a bad or failing PSU. This is quite dangerous. High voltages and hazardous chemicals are present in PSU capacitors and other components – even when main power is disconnected. You can only replace a bad PSU.

12. If you keep getting the same failures after replacing CPUs, mothersboards, and PSUs, there is a small chance that one of the peripheral cards is not compatible and causing damage or the card is conflicting with an internal inegrated component. If you have integrated video or sound, you need to turn these off before using external cards.


TS Rookie
well-written guide, thanks sir (can i publish the Turkish translation of this guide with including ur name as offical author?)


Techspot old timer.....
howard_hopkinso said:
Hi Tedster.

I have deleted your other thread, because as you can see it`s already here in this forum.

Regards Howard :)
I noticed a few of my guides had dropped off... could you repost them?


Techspot old timer.....
greenflash said:
well-written guide, thanks sir (can i publish the Turkish translation of this guide with including ur name as offical author?)
You may use or translate anything you like.


TS Rookie
Just a quik addition, I get power failures quite frequently yet all i have to do is reset/turn off and disconnect power a few times before it works again. EG: when i installed my new hdd, i started up and got no beep code yet drives etc started spinning. I held in my power button, and turned off the power at the back of the CPU, then I simply restarted and reset and then it worked again.

Good guide anyways, well done.


Just a quick note to let you know, I`ve just deleted the other thread you submitted in this forum. As you can see, It`s already here.

Regards Howard :)


Techspot old timer.....
for some weird reason, many of my posts keep dropping off.
I reposted it because it disappeared.
Hey no problem mate.

I can assure you your thread has always been here from the start of this forum.

If you are having problems, please don`t hesitate to pm me.

You are a highly valued member of Techespot and anything I can do to help is a real pleasure.

Regards Howard :)


TS Rookie
check battery

If you can not get in to the bios setup you should always first of all check the battery. Try removing the battery and you will see that the computer just gives one beep and stops, nothing happens!

Tedster said:
You just built a computer, or the one you have suddenly won't boot up.... what you have now is a P.O.S.T. Failure. (Power On Self Test).


TS Rookie
Power would turn on because It was a ram issue

The reason my Computer wouldn't turn on was because one of my Ram was bad. I bought a 2 package deal (2 x 1024) 2 gigs by Ultra DDR2 which they say is DDR2 because the have a sale to get you to buy both. Well I never realized a new ram would be bad. I ran into another problem I'm only running 1 stick at 1024 but my bios is telling me I have 512 of ram what the heck. I went into MSCONFIG and went into BOOT.INI to advance settings and cleared maxmem and applied settings and reboot computer and still shows 512. I think Ultra sent me some bogus ram. Saying it's 1024 on the sticker but really a 512. Or maybe both sticks have to be together to make it run at 2048. Do you have a solution to this matter? Is there something else I could do to get this to read 1024 instead of 512? I really can't do much in bios. I tried flashing bios. I also overclocked the ram but I set it back to default because it ran hot and I don't want to damage my ram.


Techspot old timer.....
For those unfamiliar with BIOS Beeps, refer to Howard's BIOS Beep guide in this GUIDES forum.


TechSpot Chancellor
Hi Tedster
One point - I was always told to leave the chassis plugged in to the mains. This ensures that it is earthed.
I always thought this was good advice but maybe not.........


Techspot old timer.....
NEVER UNDER ANY CIRCUMSTANCE LEAVE A COMPUTER PLUGGED INTO THE MAINS (while working on the insides.) Not only is this DANGEROUS, but you can also destroy your computer. There is NO GUARANTEE that the ground in your building's wiring is safe or installed correctly. (Especially in older structures.) Furthermore, stray currents can short your computer. To properly ground your system, run a spare wire from your computer case to a cold water pipe or properly grounded wire like a lightening arrestor or a ground disperser pad (sold in electronics stores.)

It takes very little current to kill and adult, less for children. 3 amps can kill a grown adult. While voltages are nasty and cause burns, it is the amount of current (amps) that are lethal.



TechSpot Chancellor
Jeepers, how did these posts get so mixed up?
Perhaps I should have been more specific = connect to a switched mains socket but with the power off.


TS Ambassador
There is still power supplied to the ATX motherboard when the power plug is attached to the power supply with the power switch "Off"... I use a static wrist strap connected to a wall plugs ground. These wrist straps need to be replaced often if you sweat or use them alot