no POST


L

l e o

My PC was running fine for months but today it didn't POST. I even
cleared the CMOS but it didn't work. After leaving it alone for a while,
it was working fine. Now, it doesn't POST. Can I assume the motherboard
is at fault?
 
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P

Paul

My PC was running fine for months but today it didn't POST. I even
cleared the CMOS but it didn't work. After leaving it alone for a while,
it was working fine. Now, it doesn't POST. Can I assume the motherboard
is at fault?
It could be a power supply problem.

Paul
 
R

Rod Speed

l e o said:
My PC was running fine for months but today it didn't POST. I even cleared the CMOS but
it didn't work. After leaving it alone for a while, it was working fine. Now, it doesn't
POST. Can I assume the motherboard is at fault?
Nope.

Pull all the cards out and see if it posts like that.
You can see a card stopping it from posting.

It can also be a failing power supply,
easiest check for that is to try another.

Can be something as basic as a short to case, try running
the motherboard loose on the desktop to check that possibility,
particularly if you are about to replace the motherboard.

See if any of the caps on the motherboard have failed.
Those are the usually blue or black plastic covered post
like things sticking up vertically from the motherboard.
The tops should be flat. If any have bulged or are leaking,
the cap has failed and usually the best approach is to
replace the motherboard.
 
J

John Doe

Rod Speed said:
Can be something as basic as a short to case,
Maybe if your mainboard is made in Timbuktu.

The standoffs don't contact anything except the small rings around
the holes in the mainboard.
try running the motherboard loose on the desktop to check that
possibility, particularly if you are about to replace the
motherboard.
A decent computer case is made for securely holding a mainboard,
power connectors, and add-in cards. There should be no short. I
guess you could unscrew and then remount the mainboard if you felt
like checking for strange objects/gunk/whatever you might think is
stuck to the mounting hole areas, but running the mainboard loose on
the desktop with the components, power connectors, and the video
card hanging there is a very bad idea unless you want to create
problems you don't already have. If you're worried about shorts,
keep your mainboard inside the case where it belongs. When stripped
to basic components, you can easily enough tell whether your
mainboard is faulty by replacing the few components left.
 
M

Man-wai Chang

l said:
My PC was running fine for months but today it didn't POST. I even
cleared the CMOS but it didn't work. After leaving it alone for a while,
it was working fine. Now, it doesn't POST. Can I assume the motherboard
is at fault?
Look for bulged capacitors on the motherboard...

--
.~. Might, Courage, Vision, SINCERITY. http://www.linux-sxs.org
/ v \ Simplicity is Beauty! May the Force and Farce be with you!
/( _ )\ (Ubuntu 6.06) Linux 2.6.16.20
^ ^ 15:43:02 up 10 days 1:26 0 users load average: 1.00 1.01 1.00
news://news.3home.net news://news.hkpcug.org news://news.newsgroup.com.hk
 
S

spodosaurus

John said:
Maybe if your mainboard is made in Timbuktu.
There are other ways to short the mainboard other than the standoffs.
The standoffs don't contact anything except the small rings around
the holes in the mainboard.




A decent computer case is made for securely holding a mainboard,
power connectors, and add-in cards. There should be no short.
If the world were always as it should be you'd be washing my car.
I
guess you could unscrew and then remount the mainboard if you felt
like checking for strange objects/gunk/whatever you might think is
stuck to the mounting hole areas, but running the mainboard loose on
the desktop with the components, power connectors, and the video
card hanging there is a very bad idea unless you want to create
problems you don't already have.
I agree, take care not to have the video card in a position where it
could get pushed out of its slot while the PC is running.

If you're worried about shorts,
keep your mainboard inside the case where it belongs. When stripped
to basic components, you can easily enough tell whether your
mainboard is faulty by replacing the few components left.
Rod suggested several steps before pulling the board and running it
outside the case. This is a 'last thing to try' thing that you've
latched onto. It's also easier to check underneath the capacitors (as
Rod suggested) when the board is out of the case!!


--
spammage trappage: remove the underscores to reply

I'm going to die rather sooner than I'd like. I tried to protect my
neighbours from crime, and became the victim of it. Complications in
hospital following this resulted in a serious illness. I now need a bone
marrow transplant. Many people around the world are waiting for a marrow
transplant, too. Please volunteer to be a marrow donor:
http://www.abmdr.org.au/
http://www.marrow.org/
 
D

Davy

To be honest assuming is wrong, yes it could be the mobo.... but wha
if it isn't..? A logical approach is always the best

First of all did you check the bios battery, could be duff yo
know..., a PC will POST with out any disc drives connected includin
the hard disc and a good working mobo with the RAM removed you'll ge
a series of beeps

One thing that could stop post is the graphic card, have you trie
re-seating (removing and refitting), could you lob it in another uni
just to check, we're not interested in it's drivers we just want t
know if it boots.. or you could lob a known good one in to try,
these thing's got to be woken by the bios as well or you'll won't se
anything

Could it be the power supply? Again trying it one way or the othe
will prove a point, could even be the CPU... one clue 'may' be had b
checking the fan... is it stiff or does it feel sticky when you try t
spin it... if so it would be correct to suspect the CPU

Bad or swollen caps on the mobo can do anything from nothing at all t
not working at all, their tops should be nice n' flat not looking lik
a dome and no gunge leaking either top or bottom, this gunge can b
corrosive, eating through the protective lacquer and then gobblin
the copper tracks up... if it get's in the plated through hole
you're knackered cos mobo's consist of more than one PC
(multi-layer boards) to avoid having wire links all over the place s
they sandwich a board in the middle to do the job.... hence the plate
through holes

The first goal is as you know is to get POST

Dav
 
L

l e o

l said:
My PC was running fine for months but today it didn't POST. I even
cleared the CMOS but it didn't work. After leaving it alone for a while,
it was working fine. Now, it doesn't POST. Can I assume the motherboard
is at fault?

I let the PC sit overnight. It's now working. It has happened like this
since June. Can it still be Motherboard? Or Powersuppply, video card?
 
R

Randella

Seems to me like you have a heat sensitive problem... Does your system
work all day and then if you restart it your missing the POST?

Or is it just random times?

-Randy
 
L

l e o

Randella said:
Seems to me like you have a heat sensitive problem... Does your system
work all day and then if you restart it your missing the POST?

Or is it just random times?

-Randy

seems to be. It happens only when first starting up? Do you mean I
should take the heatsink/fan out and re-sit it?
 
L

l e o

Randella said:
Seems to me like you have a heat sensitive problem... Does your system
work all day and then if you restart it your missing the POST?

Or is it just random times?

-Randy

It doesn't happen all the times; just sometimes. When it does, I have to
let it sit for a while. Once it's going, it's fine.
 
C

Charlie Wilkes

Maybe if your mainboard is made in Timbuktu.

The standoffs don't contact anything except the small rings around
the holes in the mainboard.
You're blowing smoke, oh hoarder of dirty cat litter. Yeah it could
be a short. That is what it sounds like, in fact. I had a machine
that wouldn't power up when I put the metal cover on the case, and I
fixed it with a piece of cardboard.

Charlie
 
L

larry moe 'n curly

John said:
"Rod Speed" <rod.speed.aaa gmail.com> wrote:

Maybe if your mainboard is made in Timbuktu.

The standoffs don't contact anything except the small rings around
the holes in the mainboard.
Then Timbuktu must make lots of mobos because I still find some where a
hole will have have signal traces or even power traces running very
close to a hole, and on one mobo the +3.3V power was around the left
side a hole and +5.0V power was around the right side. So I inspect
every hole, just in case.

Another problem is that the mobo or case may be warped enough to let
the two touch, making it important to support the mobo at each corner
to prevent this. If the case isn't made to accomodate a standoff for a
corner hole, I either install the standoff with the threads cut off or
put a rubber stick-on on the case there.
A decent computer case is made for securely holding a mainboard,
power connectors, and add-in cards. There should be no short. I
guess you could unscrew and then remount the mainboard if you felt
like checking for strange objects/gunk/whatever you might think is
stuck to the mounting hole areas, but running the mainboard loose on
the desktop with the components, power connectors, and the video
card hanging there is a very bad idea unless you want to create
problems you don't already have.
The only likely problems are the plug-in cards touching one another
(place cardboard between them) or popping out of their slots because
the rear bracket presses against the table top, something that can be
prevented by placing the mobo on about 3/4" of newspaper and letting
the card brackets hang over the edge.
 
R

Rod Speed

John Doe said:
Rod Speed <rod.speed.aaa gmail.com> wrote
Maybe if your mainboard is made in Timbuktu.
Nothing to do with where the mainboard is made.

And most of them are made in third world countrys anyway.
The standoffs don't contact anything except the
small rings around the holes in the mainboard.
It aint that black and white.
A decent computer case is made for securely holding a mainboard,
power connectors, and add-in cards. There should be no short.
Pity about the real world where it does happen anyway.
I guess you could unscrew and then remount the mainboard
if you felt like checking for strange objects/gunk/whatever
you might think is stuck to the mounting hole areas,
It can also be a loose screw thats ended up jammed
under the mainboard that someone didnt bother to
hunt down when it ended up free inside the case etc.
but running the mainboard loose on the desktop with
the components, power connectors, and the video
card hanging there is a very bad idea unless you
want to create problems you don't already have.
Wrong if you just want to see if it POSTs or not before replacing
the motherboard after you have eliminated the other more likely
possibilitys. The main problem with running it lose is the hassle
involved in getting it out of the case, which is why I said that its
best to only do that if you are about to replace the mainboard anyway.
If you're worried about shorts, keep your
mainboard inside the case where it belongs.
No thanks, that test allowed me to diagnose a particular
quirky fault that was proven to be an intermittent short to case.
When stripped to basic components, you can easily enough tell whether
your mainboard is faulty by replacing the few components left.
And if its a short to case, the mainboard doesnt need to
be replaced, the short just needs to be eliminated instead.
 
R

Rod Speed

I let the PC sit overnight. It's now working. It has happened like
this since June. Can it still be Motherboard?
Yes, particularly if its got bad caps or an intermittent short to case.
Or Powersuppply,
Yes. They can go intermittent like that, usually with bad solder joints.
video card?
Yes, which is why the best test for that is to wait till it wont POST
again and remove all the cards and ram and cables from the
mainboard and see if it will at least beep, whining about the lack of ram.
 
R

Rod Speed

l e o said:
It doesn't happen all the times; just sometimes. When it does, I have
to let it sit for a while. Once it's going, it's fine.
Most likely something's developed a bad solder joint or a cracked trace.
Those can be temperature sensitive like that and it can be the motherboard
or power supply. Its obviously cheaper to try another power supply first.
Can be bad caps on the motherboard too.

Can also be an improperly seated card too, or even a short to case.

There's only one viable approach with faults like this, try the possibilitys
systematically, obviously with the cheapest like trying what happens with
no cards plugged in etc first.
 
J

John Doe

spodosaurus said:
There are other ways to short the mainboard other than the
standoffs.
Yeah, like messing with it outside of the case.
If the world were always as it should be you'd be washing my car.
Hello troll.
I agree, take care not to have the video card in a position where
it could get pushed out of its slot while the PC is running.
There is an example of someone who actually tries to use the
mainboard as if it's still securely inside of the case. That's what
I'm saying you definitely should not do.

Besides the risk of your mainboard contacting things while it's
powered up outside of the case, having everything that plugs into
the mainboard hanging loose and sloshing around on your desk is a
good way to create problems.

Having a mainboard inside of the case allows you to easily ground
yourself, something mainboard manufacturers plainly tell you to do
while working with the mainboard inside of the case.

If I were doing RMA's and heard you did that, you'd be flatly
denied.

If it's your property and you aren't looking forward to using the
warranty, do whatever you like.
 
R

Randella

l said:
It doesn't happen all the times; just sometimes. When it does, I have to
let it sit for a while. Once it's going, it's fine.
When you start it up cold do you have this problem?

When you restart it after it has been on a while do you have this
problem?
From what you have said I think that you have an intermittant heat
related fault in your system. What this means is that something once
it gets hot, separates from the motherboard or a connection separates
somewhere to ground out the BIOS. Therefore when warm you receive no
post. The key to solving the puzzle is to figure out what part is
expanding when hot...

Let me know what you think...

-Randy
 
R

Rod Speed

Yeah, like messing with it outside of the case.
Completely trivial to avoid that.

Even you should be able to mange it.
Hello troll.
Wouldnt know what a troll was if it bit its lard arse.

Or dont bother with a video card or any other card at all
if the motherboard wont post and you want to see if it will
post outside the case. Just connect the speaker so you can
see if it beeps if it hasnt got the piezo on the motherboard.
There is an example of someone who actually tries to use
the mainboard as if it's still securely inside of the case.
You dont need to do that if you are checking for a short to case.
That's what I'm saying you definitely should not do.
More fool you. Its easy enough if you actually have a clue.
Besides the risk of your mainboard contacting
things while it's powered up outside of the case,
Completely trivial to avoid by putting it on something non conductive.
having everything that plugs into the mainboard
hanging loose and sloshing around on your desk
No need to have anything other than the connection
to the speaker and the power connection if you are
checking if it will post outside the case.
is a good way to create problems.
Not if you actually have a clue.
Having a mainboard inside of the case allows you to easily ground
yourself, something mainboard manufacturers plainly tell you to do
while working with the mainboard inside of the case.
You can still ground yourself fine.
If I were doing RMA's and heard you did that, you'd be flatly denied.
And I'd **** you over in the small claims court if you were
stupid enough to try pulling that stunt with a motherboard
that wouldnt post when it was still in the case.
If it's your property and you aren't looking forward
to using the warranty, do whatever you like.
We'll do that anyway. You get to like it or lump it.
 
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J

John Doe

A tough guy wanna-be troll from (comp.sys.ibm.pc.hardware.storage)


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From: "Rod Speed" <rod.speed.aaa gmail.com>
Newsgroups: alt.comp.hardware.pc-homebuilt
Subject: Re: no POST
Date: Sat, 17 Jun 2006 08:05:28 +1000
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Yeah, like messing with it outside of the case.
Completely trivial to avoid that.

Even you should be able to mange it.
Hello troll.
Wouldnt know what a troll was if it bit its lard arse.

Or dont bother with a video card or any other card at all
if the motherboard wont post and you want to see if it will
post outside the case. Just connect the speaker so you can
see if it beeps if it hasnt got the piezo on the motherboard.
There is an example of someone who actually tries to use
the mainboard as if it's still securely inside of the case.
You dont need to do that if you are checking for a short to case.
That's what I'm saying you definitely should not do.
More fool you. Its easy enough if you actually have a clue.
Besides the risk of your mainboard contacting
things while it's powered up outside of the case,
Completely trivial to avoid by putting it on something non conductive.
having everything that plugs into the mainboard
hanging loose and sloshing around on your desk
No need to have anything other than the connection
to the speaker and the power connection if you are
checking if it will post outside the case.
is a good way to create problems.
Not if you actually have a clue.
Having a mainboard inside of the case allows you to easily ground
yourself, something mainboard manufacturers plainly tell you to do
while working with the mainboard inside of the case.
You can still ground yourself fine.
If I were doing RMA's and heard you did that, you'd be flatly denied.
And I'd **** you over in the small claims court if you were
stupid enough to try pulling that stunt with a motherboard
that wouldnt post when it was still in the case.
If it's your property and you aren't looking forward
to using the warranty, do whatever you like.
We'll do that anyway. You get to like it or lump it.
 

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