Computer won't turn on!

About 4 months ago, my computer wouldn't turn on.

It has an Asus mobo with an ATX power supply. I turn it on and off at
least once a day.

I pressed the on button about 10 times and finally it went on.

A couple months later, I had to press the on button about 30 times and
it went on.

I figured the problem was the on button and I went through my old
parts to find another momentary switch with wires and 2-pin mobo
connector, and I looked at the mobo layout to know where the on/off
switch connnected.

Today it wouldn't go on so I connected the other switch. Still didn't
work. Reconnected first switch and after 30 more pushes, slow, fast,
computer turned on.

The resistance of the other switch when closed is about 0.2 ohms.

Does my mobo have a problem? Or what?


It will run for hours and hours after it's on, and Asus Probe shows
the voltages are very stable. 1.776, 3.296 - 3.312, 4.999 - 5.026,
and 12.099.

Thanks.

mm wrote:

> Computer won't turn on!
>
> About 4 months ago, my computer wouldn't turn on.
>
> It has an Asus mobo with an ATX power supply. I turn it on and off at
> least once a day.
>
> I pressed the on button about 10 times and finally it went on.
>
> A couple months later, I had to press the on button about 30 times and
> it went on.
>
> I figured the problem was the on button and I went through my old
> parts to find another momentary switch with wires and 2-pin mobo
> connector, and I looked at the mobo layout to know where the on/off
> switch connnected.
>
> Today it wouldn't go on so I connected the other switch. Still didn't
> work. Reconnected first switch and after 30 more pushes, slow, fast,
> computer turned on.
>
> The resistance of the other switch when closed is about 0.2 ohms.
>
> Does my mobo have a problem? Or what?

Or PSU. What does your PS-ON voltage do when you engage the ON switch?

On Wed, 04 May 2011 20:38:49 -0400, mm <(E-Mail Removed)>
wrote:

>Computer won't turn on!

I forgot to say that the green LED on the mobo is always lit during my
efforts to get the computer to turn on.


One URL I looked at says "Make sure all memory and peripheral cards
are fully seated. If it still won't start, you'll have to consider
failure of the motherboard."

I actually have a 500MB DIMM that used to work. I took it out and used
it with no problem in another computer, then removed it from the other
computer and put it back in this one, but I keep trying to seat it
right and it never shows up in the boot-up memory count-off or in
System Properties. (Only the one gig DIMM shows up.) Yesterday it
clicked in louder than ever before, but still isn't "there'. Its slot
is on the other side of the board from the on/off switch connector.

Is this a separate problem or might it be related?

Thanks.

On 5/4/2011 5:38 PM, mm wrote:
> Computer won't turn on!
>
> About 4 months ago, my computer wouldn't turn on.
>
> It has an Asus mobo with an ATX power supply. I turn it on and off at
> least once a day.
>
> I pressed the on button about 10 times and finally it went on.
>
> A couple months later, I had to press the on button about 30 times and
> it went on.
>
> I figured the problem was the on button and I went through my old
> parts to find another momentary switch with wires and 2-pin mobo
> connector, and I looked at the mobo layout to know where the on/off
> switch connnected.
>
> Today it wouldn't go on so I connected the other switch. Still didn't
> work. Reconnected first switch and after 30 more pushes, slow, fast,
> computer turned on.
>
> The resistance of the other switch when closed is about 0.2 ohms.
>
> Does my mobo have a problem? Or what?
>
>
> It will run for hours and hours after it's on, and Asus Probe shows
> the voltages are very stable. 1.776, 3.296 - 3.312, 4.999 - 5.026,
> and 12.099.
>
> Thanks.


There is some history of weak/dead BIOS/CMOS batteries causing this, so
try that first. At worst case, you've spent $1-4 and not much time. But
it's not the "most likely" cause.


ATX "turn-on" is a function of both the power slurpie and the muddaboad.

It's not an uncommon problem, thanks to the "capacitor plague". It could
be the mobo, the power supply, or both.

http://en.wikipedia.org/wiki/Capacitor_plague

It's not perfect, but your eyes are the best piece of test equip-ment
for this. Most 'bad caps' will show leakage or bursting. You can see
some pics of'bad caps' on the above Wiki, but here's a few more:
http://peek.snipurl.com/27t1am [www_bing_com]
http://www.youtube.com/watch?v=oDGjWOabJ2E
http://capacitorlab.com/visible-failures/index.htm

Didn't find many pics in a hurry, but a good site;'
http://badcaps.net/

You may not be able to see those inside the power supply without opening
it. Don't do that unless you are either :
a qualified electronic tech
damned lucky
(I'm both)
If you don't feel safe opening that box, just replace it (more on that
later)

The switch is most likely not the problem, as I've powered up ATX mobos
and powerslurpies with a 1 K resistor.

Solving the problem is a Scientific Wild-Assed Guess item, as you've not
provided any further info on your gear... *HINT* (Age/era would help)

ASUS has had their share of bad caps, so the muddaboad is still a possible.

Right now, if I were to do troubleshooting by swapout on this, I'd go
with the power supply first. With some exceptions, a current model of
power supply can be substituted "backwards in time" to much earlier ATX
stuff.





--
"**** this is it, all the pieces do fit.
We're like that crazy old man jumping
out of the alleyway with a baseball bat,
saying, "Remember me mother****er?"
Jim “Dandy” Mangrum

mm wrote:
> Computer won't turn on!
>
> About 4 months ago, my computer wouldn't turn on.
>
> It has an Asus mobo with an ATX power supply. I turn it on and off at
> least once a day.
>
> I pressed the on button about 10 times and finally it went on.
>
> A couple months later, I had to press the on button about 30 times and
> it went on.
>
> I figured the problem was the on button and I went through my old
> parts to find another momentary switch with wires and 2-pin mobo
> connector, and I looked at the mobo layout to know where the on/off
> switch connnected.
>
> Today it wouldn't go on so I connected the other switch. Still didn't
> work. Reconnected first switch and after 30 more pushes, slow, fast,
> computer turned on.
>
> The resistance of the other switch when closed is about 0.2 ohms.
>
> Does my mobo have a problem? Or what?
>
>
> It will run for hours and hours after it's on, and Asus Probe shows
> the voltages are very stable. 1.776, 3.296 - 3.312, 4.999 - 5.026,
> and 12.099.
>
> Thanks.

Is this an Asus motherboard with an AGP slot ?

Please state the Asus motherboard model number.

My Asus "P4B" motherboard, revision 1.05 was one of the first
1.5V AGP motherboards to be equipped with "AGP Warn" circuit. That
circuit looks at two signals in the AGP slot, to detect whether the
user has plugged a 3.3V video card into a 1.5V motherboard. Some earlier
boards got blown, because the video card lacked the correct keying pattern
on the edge connector. For a period of a couple years, Asus added
"AGP Warn" as a protection against such damage. A typical mis-keyed
AGP video card might have been SIS305 based.

"AGP Warn" comes in two flavors. Mine is the "full" version, with a
red colored LED soldered in place. If the "AGP Warn" is triggered, the
red LED comes on, and the motherboard won't start. Basically, PS_ON#
is gated off, using two transistors, if the wrong status information
is coming from the AGP slot. By preventing the power from coming on,
the AGP slot can't be blown out.

To reduce costs, later versions still had the two transistors, but they
removed the red LED. That meant the circuit no longer had visual feedback.
But the transistors could still keep the power off.

On a couple occasions, people have had "AGP Warn" malfunction, and
turn off the computer because the circuit was fooled into thinking
an illegal video card was installed.

So, please mention the motherboard model number. If it's a "P4B",
you might also want to check whether it's version 1.05 or greater.

Paul

"mm" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Computer won't turn on!
>
> About 4 months ago, my computer wouldn't turn on.
>
> It has an Asus mobo with an ATX power supply. I turn it on and off at
> least once a day.
>
> I pressed the on button about 10 times and finally it went on.
>
> A couple months later, I had to press the on button about 30 times and
> it went on.
>
> I figured the problem was the on button and I went through my old
> parts to find another momentary switch with wires and 2-pin mobo
> connector, and I looked at the mobo layout to know where the on/off
> switch connnected.
>
> Today it wouldn't go on so I connected the other switch. Still didn't
> work. Reconnected first switch and after 30 more pushes, slow, fast,
> computer turned on.

You can easily eliminate the switch problem by using a screw driver to
briefly connect the 2 motherboard pins that control the power - that is all
the switch does for you. This may or may not help!

"Nobody > (Revisited)" <(E-Mail Removed)> wrote in message
news2qwp.13566$(E-Mail Removed)...
> On 5/4/2011 5:38 PM, mm wrote:
>> Computer won't turn on!
>>
>> About 4 months ago, my computer wouldn't turn on.
>>
>> It has an Asus mobo with an ATX power supply. I turn it on and off at
>> least once a day.
>>
>> I pressed the on button about 10 times and finally it went on.
>>
>> A couple months later, I had to press the on button about 30 times and
>> it went on.
>>
>> I figured the problem was the on button and I went through my old
>> parts to find another momentary switch with wires and 2-pin mobo
>> connector, and I looked at the mobo layout to know where the on/off
>> switch connnected.
>>
>> Today it wouldn't go on so I connected the other switch. Still didn't
>> work. Reconnected first switch and after 30 more pushes, slow, fast,
>> computer turned on.
>>
>> The resistance of the other switch when closed is about 0.2 ohms.
>>
>> Does my mobo have a problem? Or what?
>>
>> It will run for hours and hours after it's on, and Asus Probe shows
>> the voltages are very stable. 1.776, 3.296 - 3.312, 4.999 - 5.026,
>> and 12.099.
>>
>> Thanks.
>
> There is some history of weak/dead BIOS/CMOS batteries causing this, so
> try that first. At worst case, you've spent $1-4 and not much time. But
> it's not the "most likely" cause.

Just incase you are skeptical about this - it is sound advice. I was
skeptical before I had a PC which wouldn't start until I'd replaced the cmos
battery (needless to say with a fresh not second hand one).
--
Brian Cryer
http://www.cryer.co.uk/brian

mm wrote:
> Computer won't turn on!
>
> About 4 months ago, my computer wouldn't turn on.
>
> It has an Asus mobo with an ATX power supply. I turn it on and off at
> least once a day.
>
> I pressed the on button about 10 times and finally it went on.
>
> A couple months later, I had to press the on button about 30 times and
> it went on.
>
> I figured the problem was the on button and I went through my old
> parts to find another momentary switch with wires and 2-pin mobo
> connector, and I looked at the mobo layout to know where the on/off
> switch connnected.
>
> Today it wouldn't go on so I connected the other switch. Still didn't
> work. Reconnected first switch and after 30 more pushes, slow, fast,
> computer turned on.
>
> The resistance of the other switch when closed is about 0.2 ohms.
>
> Does my mobo have a problem? Or what?
>
>
> It will run for hours and hours after it's on, and Asus Probe shows
> the voltages are very stable. 1.776, 3.296 - 3.312, 4.999 - 5.026,
> and 12.099.
>
> Thanks.

Could be several things, but the most likely is the power supply. What
happens is the capacitors in the supply get weak and the voltage does
not come up fast enough. Constant attempts at turning it on charges up
those caps so that eventually they reach the proper voltage in order to
stay up. Eventually they get so weak that even the consistent retries
fail to work. Try another PS of equal or greater wattage.

mm wrote:
> On Wed, 04 May 2011 20:38:49 -0400, mm <(E-Mail Removed)>
> wrote:
>
>> Computer won't turn on!
>
> I forgot to say that the green LED on the mobo is always lit during my
> efforts to get the computer to turn on.
>
>
> One URL I looked at says "Make sure all memory and peripheral cards
> are fully seated. If it still won't start, you'll have to consider
> failure of the motherboard."
>
> I actually have a 500MB DIMM that used to work. I took it out and used
> it with no problem in another computer, then removed it from the other
> computer and put it back in this one, but I keep trying to seat it
> right and it never shows up in the boot-up memory count-off or in
> System Properties. (Only the one gig DIMM shows up.) Yesterday it
> clicked in louder than ever before, but still isn't "there'. Its slot
> is on the other side of the board from the on/off switch connector.
>
> Is this a separate problem or might it be related?
>

Is the motherboard spec'ed to handle that much memory? That kind of memory? Some
DDR memories, for instance, would not work with certain "older" motherboards.

mm wrote:

>Computer won't turn on!
>
> I forgot to say that the green LED on the mobo is always lit during my
> efforts to get the computer to turn on.

That's important because when that LED stays dim, the problem is
almost always the PSU or a short. But if the LED does light up, it
can still be the PSU, and the need for multiple turn-on attempts point
to worn out electrolytic capacitors in the PSU.

> One URL I looked at says "Make sure all memory and peripheral cards
> are fully seated. If it still won't start, you'll have to consider
> failure of the motherboard."

Usually only an AGP card or 1x PCI-E card (narrow connector) will be
unseated, unless the computer has recently been moved, worked on, or a
cable in back has been installed or tugged.
Another thing to consider is a short between the motherboard and case,
usually around one of the mounting holes (screw needs electrically
insulating washer on top or bottom of hole) or at a corner (not
supported, can flex enough to short -- install rubber stick-on bumper
foot at corner, to case).

> I actually have a 500MB DIMM that used to work. I took it out and used
> it with no problem in another computer, then removed it from the other
> computer and put it back in this one, but I keep trying to seat it
> right and it never shows up in the boot-up memory count-off or in
> System Properties. (Only the one gig DIMM shows up.) Yesterday it
> clicked in louder than ever before, but still isn't "there'. Its slot
> is on the other side of the board from the on/off switch connector.
>
> Is this a separate problem or might it be related?

Take a flashlight and magnifying glass and look at each contact of the
DIMM sockets because sometimes there's a piece of junk in them (broken
piece of plastic, tiny surface mount part that tore off, or even a
piece of solder), or a contact can get mangled (you may be able to
straighten it with a dental pick or jeweler's screwdriver). Some
DIMMs just don't get along with one another, but if your 500MB DIMM
doesn't have chips whose brand marks can be read easily, then it could
be slightly defective. Name brand does not mean Kingston, Corsair,
Patriot, Mushkin, or G.Skill but the name of an actual chip maker,
like Samsung, Hynix, Micron, or Nanya.