can PSU fry a Motherboard?

  • Thread starter Thread starter Mark Smith
  • Start date Start date
M

Mark Smith

hi,

My hand-me-down P3 733 based system was giving problems with the power
supply fan for some days - the fan would not always run, it had to be tapped
a bit to make it run, and then it would run and stop again. Anyways,
yesterday there was a noise from the PSU ( like when a fuse blows ), and
then a burning smell, but the system kept on running. I switched it off
after a while and switched it on again, and it worked for a while before it
switched itself off, never to switch on again. I would get nothing on power
on - no fan movement, no POST, no beep. So i bought a compatible PSU of the
same wattage, and put that in. Still nothing - I get no POST, no beep, no
fan movements, nothing at all.

Is it possible that overheating/overloading of/by the PSU may have caused
the motherboard or the CPU to get destroyed. I gave the system at a repair
place now - waiting to hear from them. I thought of getting the viewpoint of
the ng.

thanks,
ms
 
hi,

My hand-me-down P3 733 based system was giving problems with the power
supply fan for some days - the fan would not always run, it had to be tapped
a bit to make it run, and then it would run and stop again. Anyways,
yesterday there was a noise from the PSU ( like when a fuse blows ), and
then a burning smell, but the system kept on running. I switched it off
after a while and switched it on again, and it worked for a while before it
switched itself off, never to switch on again. I would get nothing on power
on - no fan movement, no POST, no beep. So i bought a compatible PSU of the
same wattage, and put that in. Still nothing - I get no POST, no beep, no
fan movements, nothing at all.

Is it possible that overheating/overloading of/by the PSU may have caused
the motherboard or the CPU to get destroyed. I gave the system at a repair
place now - waiting to hear from them. I thought of getting the viewpoint of
the ng.

thanks,
ms
Click to expand...

Yes it's possible if the PS went AC and pumped AC through the
board/CPU.Also recently I had to do a fix on a system(Replace MB)
because of a shoddy build a hard drive locking screw had worked it's
way under the mother board and shorted it.This is why I recommend that
if the mother board comes with a thin plastic foam underlay you place
it under the mother board when fitting.

HTH :)




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thanks for the reply...

Is there any guaranteed way of knowing if the motherboard is gone? If it
comes to replacing it, can I use the existing RAM? Since this is a P3
motherboard, replacements might be hard to get - I located this one -
http://www.iwillusa.com/products/ProductDetail.asp?vID=7 - this shld suffice
for me, no? I would like to use as much of the components as I can ( to
keep the costs low ) - so I plan to use the existing HDD, etc. That should
be OK?

ms
 
thanks for the reply...

Is there any guaranteed way of knowing if the motherboard is gone? Only by replacement .
If it
comes to replacing it, can I use the existing RAM?
Click to expand...
If it's not been damaged then yes.
Since this is a P3
motherboard, replacements might be hard to get - I located this one -
http://www.iwillusa.com/products/ProductDetail.asp?vID=7 - this shld suffice
for me, no? I would like to use as much of the components as I can ( to
keep the costs low ) - so I plan to use the existing HDD, etc. That should
be OK?
Click to expand...

Hopefully :)



--
Free Windows/PC help,
It's a G not a J in jmx to reply :)
http://www.geocities.com/sheppola/trouble.html
Free songs download,
http://www.soundclick.com/bands/8/nomessiahsmusic.htm
 
hi,

My hand-me-down P3 733 based system was giving problems with the power
supply fan for some days - the fan would not always run, it had to be tapped
a bit to make it run, and then it would run and stop again. Anyways,
yesterday there was a noise from the PSU ( like when a fuse blows ), and
then a burning smell, but the system kept on running.
Click to expand...

At this point I have to ask, WHAT WHERE YOU THINKING?

Did it not occur to turn off the system when the fan stopped, or
ESPECIALLY after the noise and burning smell?

When your car oil light goes on and the temp rockets out of sign, do
you keep driving till the engine locks up? You'ne ruined the power
supply for no reason, it probably only needed a fan lube or new fan.
but now at a minimum it needs replaced. Sorry if that sounds harsh.


I switched it off
after a while and switched it on again,
Click to expand...

So KNOWING that something went wrong in the power supply, you decided
to see how much damage it'd do to the system?
and it worked for a while before it
switched itself off, never to switch on again. I would get nothing on power
on - no fan movement, no POST, no beep. So i bought a compatible PSU of the
same wattage, and put that in. Still nothing - I get no POST, no beep, no
fan movements, nothing at all.

Is it possible that overheating/overloading of/by the PSU may have caused
the motherboard or the CPU to get destroyed. I gave the system at a repair
place now - waiting to hear from them. I thought of getting the viewpoint of
the ng.
Click to expand...

The power supply is damaged and it probably blew the board. The CPU
may be fine or perhaps when the board blew, but you kept trying to run
the system, then the CPU might've been damaged too. There's still a
good chance the CPU is ok though.

Tell the repair shop to stop their work on it, and beg them not to
charge you if they' haven't looked at it yet. They will charge far
more than it's worth. A 733Mhz P3, motherboard, and adequate power
supply (used but still working) are only worth ~ $40-65 total.

If the case will allow adequate ventilation for a more modern combo,
you ought to replace the power supply, CPU, and motherboard. If all
you want is a working 733Mhz system again, nothing faster, then you
can save a few dollars by getting a motherboard compatible with the
CPU, hopefully also being Tualatin / FCPGA2 compatible, so if the old
P3 CPU works you can reuse it, but if not at least it's only $40 more
for a 1.4GHz Tualatin Celeron. In that situation a 250W power supply
(name-brand) should suffice, but 300W or larger for a newer Athlon or
P4 platform.


Dave
 
Power supply had to output excessive voltage to have damaged
motherboard. But any acceptable power supply is also required
to have overvoltage protection - just so that this type of
damage does not happen.

Did your power supply have the essential OVP or was it one
purchased without specifications and only on price? Therein
lies reasons for failure.

Did failure happen? A new power supply (containing
essential functions and a higher price) could be connected to
motherboard. If motherboard smokes or power supply does not
maintain properly voltages, then motherboard is toast.
However if motherboard is good (and is connected to speaker
and contains a working CPU), then speaker will beep.

Overvoltage problems rarely damage CPUs because they are
isolated from PSU by another power regulator.

In the meantime, learn the most important lesson. Power
supplies selling for less provide less - such as the essential
OVP - required so that a power supply cannot damage
motherboard, RAM, disk drive, etc.

Mark Smith wrote:
...
 
w_tom said:
In the meantime, learn the most important lesson. Power
supplies selling for less provide less - such as the essential
OVP - required so that a power supply cannot damage
motherboard, RAM, disk drive, etc.
Click to expand...

What about thermal protection to shut down the power in case of
overheating? Almost no retail ATX PSUs have it, but shouldn't it be
essential?

According to www17.tomshardware.com/howto/20030609/power_supplies-09.html
, in which higher priced 400W+ PSUs were reviewed, only 2 out of 13
models shut down when they became very hot (Chieftec, Verax).

I tested some of my PSUs by shorting their thermal sensors to simulate
overheating (I couldn't risk damaging them by actually making them too
hot), but none shut down, except for one whose brand is never
regularly sold on the retail market. I also read that a certain 300W
Lite-On shuts down when overheated (or even when its fan stops), but
this is another brand that's hard to buy. My 350W Fortron/Sparkle has
an empty space on its circuit board for a second thermistor, but I
can't figure out its purpose, and a variable resistor put in its place
didn't seem to do anything. On the other hand, I managed to add
rudimentary thermal protection to some of the PSUs, but it doesn't
shut down everything, just the main voltages (standby remains on),
because it works only on the low voltage side of the PSUs.
 
ATX spec does not require thermal protection. If the fan is
moving even slightest of air, then sufficient cooling should
exist in that power supply. Most heatsinks need only 200 LFM
to provide significant cooling. Notice how gentle a 200 LFM
airflow is. However if a power supply does overheat, then
what happens? Power supply fails - and still nothing else is
damaged.

Power supply again will not damage other computer components
- if it contains essential and required functions.
Unfortunately, too many supplies don't include those
requirements when sold only on price - and not on functional
specifications.
 
Thanks for all the pieces of advice. I know I deserved the tongue-lashing I
got from some you :-(

So, this afternoon the repair place calls me up and says the computer is all
done. I ask what was the problem, and they say, "too much dirt inside the
PC". So I go there, and he shows me - the computer booted up nice and good.
I paid him $30 ( this was his charge to make a diagnosis - he had told me
about this in advance ). Right now, I am writing this from the same PC that
would not even make a beep.

Before I had made a posting to this ng, I had bought a no-name PSU from
another store. The computer is now running on that PSU. But, I learnt from
my mistake - I am going back to trade it in for a name brand one -
preferably with some/all of the features you guys have been talking about.

Thank you to all those who responded.

ms
 
Thanks for all the pieces of advice. I know I deserved the tongue-lashing I
got from some you :-(
Click to expand...

It is all done in good spirits. Not so much a criticism as to help
others learn... what to do, and what not to do... knowledge is
always the goal. You have helped someone by not only documenting your
problem, but replying with the outcome, which a lot of people don't
do.


Dave
 
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