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Short overview of how to troubleshoot bad hardware when a pc does not post

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So, if your PC is old or new and it does not boot or has no display then what do you do?

Precautions :
-During connecting or disconnecting devices, be sure to have the AC electrical power disconnected
-Temporarily ground yourself, or use a wrist strap to prevent electric static discharges from destroying certain components.

Here are my troubleshooting procedures:

-With a new motherboard: verify if all mounting standoffs' holes correspond with the holes in the motherboard!!
   Or test the motherboard outside the case, on a wooden  (non conductive) surface
-Clean the system from dust, then  test with the minimum setup:
 - Disconnect all peripherals devices (including the drives, CD, DVD, printers and keyboard) and network cables, except for the motherboard + CPU + 1 ram stick, video card, monitor and power supply
-Verify that the 4-, 6- or 8-pin CPU Aux power plug is connected
-Verify that the VIDEO card has a power connecter - if yes, connect the power to it!

Now, power-on  your PC.  On boot, do you have a display?
-if NO it is one of the connected devices: RAM, Power supply , video card or monitor.  So, if possible, swap ram, power supply, video card or monitor - leaving only motherboard and CPU
-test the ram in each slot, sometimes you have abad slot, causing ram problems
-if YES, then disconnect the AC electrical power, and start reconnecting each of the peripherals, devices and cables (one at a time) until the problem shows itself.  Before each of these reconnections, you need to follow the precautions above.
*** note : if the fans are running, this shows there is 12 V present from the power supply; this does not mean the power supply is ok, you still need 3.3 V and +5 V as well; and other signals.

Additional tests and things to try :
-boot without ram, it should beep; (also, without video card)
-try the bios default settings, (if possible) or clear the bios by removing AC and the bios battery
-renew the CPU heat paste, and verify that the heat sink is mounted flat on the CPU, allowing for a good thermal contact
-you can also check the motherboard for bad capacitors as shown here :   http://en.wikipedia.org/wiki/Capacitor_plague
- test parts on another  PC to know what is ok - and what not - if possible
***note :  if you are using 4 sticks - note that many boards do not run well with the ram bus loaded heavily like that, causing deterioration of signal levels and wave forms ! --> so test with 2 sticks max ..

The term POST refers to the Power On Self Test  procedure - here a link  with a short explanation  http://www.pchell.com/hardware/beepcodes.shtml
31
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Author:nobus
19 Comments

Administrative Comment

by:Articles101
nobus,

The 300 word minimum is an EE requirement for articles.  Individual Page Editors might allow fewer words for a good article in the FAQs or Tips/Tricks category.

In addition to what I posted above, I suggest you consider the following:

(1) Tell what "post" means in a way that a wider audience would understand what that means.
(2) Tell about making sure the power is disconnected.
(3) Do you want to say anything about static discharge precautions.
(4) Spell-out mobo and then run a spell check to find at least two typos.
and
(5) If this is only about the motherboard then mention the motherboard in the title.

Articles101
Articles Admin.
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Expert Comment

by:Ravi Agrawal
My yes vote:

Well written, at least for me to understand.

Ravi.
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Expert Comment

by:AnilKumarSharma
Good article. Yes.
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Expert Comment

by:nzrasta
Very nice and easy to understand thank you will post my results when done.
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Author Comment

by:nobus
thanks to all - keep voting!
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Expert Comment

by:Morgan
Well done.
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Author Comment

by:nobus
neonate : thanks!
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Expert Comment

by:CBB
Very nice
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Expert Comment

by:BhanaD2
Replaced Power supply - Fixed the Problem

Dal
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Author Comment

by:nobus
tx guys!
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Expert Comment

by:Anjeneya Murthy
Nice article. Simple and easy to understand.

I did not know this!! :)
*** note : if the fans are running, this shows there is 12 V present from the power supply; this does not mean the power supply is ok, you still need 3.3 V and +5 V as well; and other signals.

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Author Comment

by:nobus
you can say lots more on it, but then it's not a short overview :))
tx for the vote
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Expert Comment

by:Fred Marshall
nobus:  Thank you!
Now and then I re-read this to remind myself of something I may have forgotten.
Today I have an issue that's not covered here that I could find:

The power supply does not turn on.  (Replaced it with a new one).  No fans, no lights, nada.
The caps look good.
I removed all the memory, disconnected all the peripherals power and still the same thing.

I didn't clear the BIOS.
I didn't fiddle with the CPU mount.
That's because I doubted these would matter.  Would it?
Surely marginal heatsinking isn't going to stop the PSU from turning on.
I don't know how the BIOS gets involved in the feedback from the MOBO to the PSU.  Does it?
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Author Comment

by:nobus
@fmarshall what system are you talking about? or what Q ?
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Expert Comment

by:Fred Marshall
nobus:  Sorry, if I was unclear:
Today I have an issue that's not covered here that I could find:
 The power supply does not turn on.  (Replaced it with a new one).  No fans, no lights, nada.
 The caps look good.
 I removed all the memory, disconnected all the peripherals power and still the same thing.
The condition where the power supply doesn't turn on at all AND the issue isn't the power supply itself doesn't jump out at me.  Granted I don't see this happen very often but I was left with the question.  Since then, my research suggests that it's not an often-mentioned problem.

Since then, you told me separately that clearing the BIOS would be a good idea as would checking the CPU pins.  These turned out to not be the issue in this one case but here I figure you're more about how to tackle such things.

So now I understand:
I didn't clear the BIOS originally thinking it wouldn't matter and asked: Would it?  I understand now that the answer is Yes.
I didn't fiddle with the CPU mount thinking it wouldn't matter and asked: Would it?  I understand now that the answer is also Yes.
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Author Comment

by:nobus
in general, when a problem arises, you advance by eleiminating possible problem items, till the problem cause is found
that's why you need to follow in this case the bios sequence, and check all partts
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Expert Comment

by:fred hakim
The step that always gives me the most heartburn, is after you have eliminated all the connected items (memory, video, PSU) and are left with deciding between the motherboard and the CPU.  

Sometimes, I don't have an available good matching part (correct socket/gen).  But even if I do I'm reluctant to put a possible bad CPU into a good mobo, or even more, a good CPU into a possible bad Mobo for testing,  my fear is a failing part could damage the good part I use for testing.   Am I just being paranoid?  How do you make that decision?
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by:nobus
chances are  : bad mobo = 95 % - - bad cpu = 5%
so the choice is easily made
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Expert Comment

by:Fred Marshall
You might briefly mention asking the question "is it worth it? for some of this.  It depends on the intended audience.
I tend to always replace the power supply first.  It's easy, it's cheap and there are generally PSUs on the shelf.
 I'd say the same: PSU 95% Memory 5%.
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