Bad PC (CPU?) - No boot, no beep, pls help!

[Michael Hawes]

To test, you only need PSU, motherboard & CPU. Disconnect EVERYTHING
else. System should give No Memory and video error codes. If no beeps, one
or more of those 3 is duff! If beeps, add memory and test again, then add
video card etc....
Mike.

 

[Rod Speed]

You guys are great. Should hopefully have a solution soon today. By
the way, if there is a short between case and board, does that destroy
the board?

Normally not, its usually fine when you remove the short.

 

[Rod Speed]

That can happen when the solder mask isnt cut thru by the mounting stud and
that happens later with a bit of wriggling of the case or just thermal effects.

Yeah, this system was built in June and has had no problems up to now.
I would think that if there was a short, I wouldn't get fans running, etc,

The fans just show that the motherboard is getting 12V. The short
can stop the cpu starting and so you dont get any POST etc.

I thought that the mobo would just be dead...

Nope, it usually doesnt kill the motherboard.

 

[Rod Speed]

a short can be pretty unpredictable as far as its symptoms and what it
destroys (or the lack of distruction)

Yeah, had one with some very intermittent symptoms, basically the
main IDE controller went missing and that symptom would come
and go due to cards being inserted and removed, just because it
would wriggle the motherboard on the mounting stub and so the
short itself would come and go. Worked fine outside the case,
loose on the desktop.

 

[bishnu101]

if it is a pentium 4 pc pls dis assemble all the part and kept all
those parts out side care fully for a period of 24 hours.even u have to
remove the CMOS BATTERY. after 24 hour ur bios will set to default
autometically. and there is a chance of 90 % that u will get ur pc
working fine.


if there is still any such error pls mail me

 

[Mista Fadedglory]

if it is a pentium 4 pc pls dis assemble all the part and kept all
those parts out side care fully for a period of 24 hours.even u have to
remove the CMOS BATTERY. after 24 hour ur bios will set to default
autometically. and there is a chance of 90 % that u will get ur pc
working fine.


if there is still any such error pls mail me

Well, i'm going to tell you guys the results since you have been so
great.

got a new CPU today, loaded it all up in the case and flipped the
switch... Still no bootie...

So, i had a new mobo, new PSU, new CPU and old case. took the mobo out
of the case and just ran it on a box. Voila! it worked...!!!

So, the case was shorting out my computer. Went down and bought a new
case for 35 bucks and am computing away... So, there is the end of the
tale. thanks for all the input. Hopefully it won't happen again!

 

[JAD]

Well, i'm going to tell you guys the results since you have been so
great.

got a new CPU today, loaded it all up in the case and flipped the
switch... Still no bootie...

So, i had a new mobo, new PSU, new CPU and old case. took the mobo out
of the case and just ran it on a box. Voila! it worked...!!!

So, the case was shorting out my computer. Went down and bought a new
case for 35 bucks and am computing away... So, there is the end of the
tale. thanks for all the input. Hopefully it won't happen again!

Well whatcha know a latent short. Goes to show ya never know....wonder where
or what caused it?

 

[Rod Speed]

(e-mail address removed) wrote

Well, i'm going to tell you guys the results since you have been so great.

got a new CPU today, loaded it all up in the case and flipped the switch... Still no bootie...

Urk. Not unusual tho, its very rare to kill a cpu without doing something
really stupid like killing it by overclocking with silly Vcore voltages etc.

So, i had a new mobo, new PSU, new CPU and old case. took the
mobo out of the case and just ran it on a box. Voila! it worked...!!!

So, the case was shorting out my computer.
Went down and bought a new case

You likely could have just inspected the bottom of the motherboard
and seen where a metal stud was shorting to the motherboard and
just replaced that metal stud with a plastic standoff

for 35 bucks and am computing away... So, there is the end of
the tale. thanks for all the input. Hopefully it won't happen again!

Thanks for the washup, particularly now that its turned out to be a bit unusual.

 

[Rod Speed]

Well whatcha know a latent short. Goes to show ya never
know....wonder where or what caused it?

Its almost always a metal mounting stud used where the
motherboard design doesnt have a full solder land all
around where the stud goes. The solder mask usually
does insulate adequately for a while but that gives way
after a while and you get conduction to the stud top
often after a bit of wriggling of the motherboard due
to insertion of cards and ram etc.

 

[JAD]

Its almost always a metal mounting stud used where the
motherboard design doesnt have a full solder land all
around where the stud goes. The solder mask usually
does insulate adequately for a while but that gives way
after a while and you get conduction to the stud top
often after a bit of wriggling of the motherboard due
to insertion of cards and ram etc.

I was looking at some older boards p3v4x and some Anxxx all the mounts on
these are indentical (meaning the ground trace is rather large and
,,,obvious). I personally never had one come across my bench where the
mainboard was grounded through the mount, but many with the loose screw
dropped between the mainboard and the backplate (while mounting harddrives
is my guess), sort of just waiting for that spring cleaning jossling.
murphy, gotta love him.

 

[phil paxton]

OK, so here's the situation:

I left for work on saturday with the computer running, came home and
there was just the orange light on the monitor (novideo light). The PC
was still running, but I was getting nothing.

#1: Has everyone who has touched the machine wearing their wristbands?
(I can't touch hardware, even with a band on both wrists. I have to
walk the missus thru it doing it and if she's not handy, head down to
CompUSA (they're about five miles from the house. or one of the two
restoration stores across the parking lot. I can't do it, even with a
strap on both wrists. In my case, I inherited it from a parent..

the Motherboard LED is on, the fans are spinning, but no drives are
powering up (not even floppy). I get nothing on the screen.
I have a good PC shop, so they have let me put in the old CPU into a
new mobo. Same problem...

if the "old" CPU isn't doing anything, could it be the CPU?

#2: Look underneath the [new] CPU and see if any of them there gold
legs are try to share the same hole. i.e., did one get bent? You'd be
surprised how often I've seen someone and everything seems to have
been plugged in and we've

If it's happened, it's generally a case of ending at the root.
Tinkering with the CPU (or components) so often and the over & over of
pulling cards in & out a lot does the same thing. specifically, using
things pushed into the mobo.

If so, you might get one chance at wiggling it back to where it belongs
as a second time might break it off at the root. You *don't* want that
to happen. And there are times one wiggle, and it's toast.. SOL: 1,
CPU: 0.

I added new RAM and even ran it without RAM, but got no beeps and no
fix.

New vid card, still no workie.

I have basically switched everything to new except for the CPU. Since
I have tried the "old" CPU in multiple mobos to no avail, do you guys
think that it's a pretty good bet that it's the CPU? Can the CPU
damage subsequent mobos if it's faulty? Anyone have a similar
situation?

:
#3: How effective would a POST card be [for diagnosing the current
problems]?

#4: Once you have things looking stable, how effective would using a
KNOPPIX disc be?

(You don't have to worry about all of the hassles of Windows &
whatnot; i.e., if you're currently running Windows.)
_______________________________

p


p.s. This is a situation where a webcam would be sooooooo cool to
diagnose a problem (if you have one good box up & running.)

 

[Rod Speed]

I was looking at some older boards p3v4x and some Anxxx all the
mounts on these are indentical (meaning the ground trace is rather
large and ,,,obvious). I personally never had one come across my
bench where the mainboard was grounded through the mount, but many
with the loose screw dropped between the mainboard and the backplate
(while mounting harddrives is my guess), sort of just waiting for
that spring cleaning jossling. murphy, gotta love him.

Yeah, you get plenty of those with amateurs inside systems.