Monitor in stand by when I turn on the computer

[vaio]

Hi,
my computer doesn't start, to be precise it turns on, I hear the fans
but monitor hang on in stand bye.
I can't hear the RAM count; no sound from internal speaker.
I don't have installed other hardware, computer was working correctly,
without problems, all of this has happened suddenly.

I have an asus motherboard with 800 mhz cpu, 512 RAM (2x256), video card
AGP asus, ethernet card, controller scsi, sound card c-media, three hard
disks (one of them is scsi).

I have tried two different monitors, another video card (PCI), I have
unplugged drives and cards, cleared the CMOS, but no results.
I have also tried with other RAM, without solving the problem.

Can you help me,
thank you and sorry for my english, I am italian.

 

[Paul]

Hi,
my computer doesn't start, to be precise it turns on, I hear the fans
but monitor hang on in stand bye.
I can't hear the RAM count; no sound from internal speaker.
I don't have installed other hardware, computer was working correctly,
without problems, all of this has happened suddenly.

I have an asus motherboard with 800 mhz cpu, 512 RAM (2x256), video card
AGP asus, ethernet card, controller scsi, sound card c-media, three hard
disks (one of them is scsi).

I have tried two different monitors, another video card (PCI), I have
unplugged drives and cards, cleared the CMOS, but no results.
I have also tried with other RAM, without solving the problem.

Can you help me,
thank you and sorry for my english, I am italian.

If it is a Slot 1 system, remove and reseat the processor.
Sometimes the connector on Slot 1 can be flaky.

Other than that, you can try another power supply, or try another
motherboard. It sounds like you've done a good job so far,
of trying to debug it.

Paul

 

[Rod Speed]

my computer doesn't start, to be precise it turns on, I hear the fans but monitor hang on in stand
bye.
I can't hear the RAM count; no sound from internal speaker.

Thats evidence that the cpu isnt starting at all.

I don't have installed other hardware, computer was working correctly, without problems, all of
this has happened suddenly.

Thats not unusual with that sort of fault.

I have an asus motherboard with 800 mhz cpu, 512 RAM (2x256), video card AGP asus, ethernet card,
controller scsi, sound card c-media, three hard disks (one of them is scsi).

I have tried two different monitors, another video card (PCI), I have
unplugged drives and cards, cleared the CMOS, but no results.
I have also tried with other RAM, without solving the problem.

Can you help me,

Something has broken and you need to work out what that is.

It could be the power supply, and its a lot
cheaper to try that than the motherboard.

Its very unlikely to be the cpu itself, they dont usually die.

If it isnt the power supply its likely the motherboard.

Check for bad caps. These are the usually blue or black plastic covered
post like things that stick up vertically from the motherboard surface. The
tops should be flat and if any of them have bulged or have leaked, the
problem is bad caps and you need to replace the motherboard.

If you have decided that the problem is likely the motherboard
and you dont plan to replace the whole system, try running the
motherboard loose on the desktop just before replacing it. You
can get a short to case that produces those symptoms and running
the motherboard loose on the desktop is the best test for that.

thank you and sorry for my english, I am italian.

Its very understandable.

 

[vaio]

Thanks to both of you.
Mine is not a slot 1 system; I will try on this afternoon with another
power supply or to run the motherboard loose on the desktop, then I'll
write it to you.
It seems that motherboard doesn't have bad caps.
Thank you again, if you have other ideas please write them to me.

 

[vaio]

I have runned the motherboard loose on the desktop but nothing to do...
I could not try with another ATX power supply, do you think it is
important to try? Motherboard is powered, fans work correctly, why it
should be che power supply?
Should I give up, thinking that it depends on the motherboard and I have
lost it?
Thank you again.

 

[Rod Speed]

I have runned the motherboard loose on the desktop but nothing to do...

You presumably mean it made no difference, it still wont start properly.

I could not try with another ATX power supply, do you think it is important to try?

Yes, if there arent any visible bad caps on the motherboard.

Motherboard is powered, fans work correctly, why it should be che power supply?

The fact that the fans spin only proves that the 12V rail is still something like 12V.

If by the motherboard powered you mean that the led on the motherboard
comes on, thats usually powered by the +5V standby rail from the power
supply. So you dont know if the main +5V rail is within specs.

And one failure mode of power supplys sees lots more ripple on some of
the rails than there should be. That wont necessarily have any visible effect
on the fans which wont care much about that. The motherboard will tho.

Should I give up, thinking that it depends on the motherboard and I have lost it?

I'd personally try another power supply because they can fail like
that and are a lot cheaper than a new motherboard or new system.

Some operations will allow you to return a power supply if it makes
no difference, but that may not be that easy to do in your country.

Thank you again.

No problem, happy to discuss it for as long as it takes.

 

[vaio]

You presumably mean it made no difference, it still wont start properly.

Yes, sorry, I meant that.

I have tried with power supply of the computer of one friend of mine,
but it doesn't start...
Thanks for all your explanations...
I suppose that now I should give up...

 

[GlowingBlueMist]

Yes, sorry, I meant that.

I have tried with power supply of the computer of one friend of mine, but
it doesn't start...
Thanks for all your explanations...
I suppose that now I should give up...

I have run into a motherboard that would not boot if a dead or weak CMOS
battery was still on the board. Clearing the CMOS in that situation did not
get the board to boot until a new battery was installed. After a new
battery and the CMOS reset again the board would boot just fine.

Another test you most likely have tried is to remove all boards and memory
and see if the bare motherboard beeps, complaining about missing memory
during a power on. The above mentioned battery failure can stop this from
testing as well.

 

[Rod Speed]

I have tried with power supply of the computer of one friend of mine,
but it doesn't start...
Thanks for all your explanations...
I suppose that now I should give up...

I would try a new battery, just because its so cheap to try,
and because you can see a bad battery produce symptoms
like you have, even tho its not very likely to be the problem.

Looks pretty clear that the motherboard has failed
and it isnt necessarily that viable to replace it, it may
well be a good time to go for a new system now.

 

[w_tom]

I have tried with power supply of the computer of one friend of mine,
but it doesn't start...
Thanks for all your explanations...
I suppose that now I should give up...

You have tried this and that - spent how long - and are still nowhere
near to even knowing what is and is not defective. You are shotgunning
- what technically naive recommend. Two minutes with a 3.5 digit
multimeter would have identified a single suspect. Power supply can
even cause a fan to spin - and still power supply is 100% defective.
That made obvious with the meter.

Now someone says replace the battery. Is original battery defective?
Again, a meter would have reported that in but seconds. A 3 volt
lithium cell would measure below 2.8 volts if ready for replacement -
and probably less than 2.4 if it causes computer failure. Others will
replace this and replace that until what is let to replace?

Best solutions start by first collecting facts long before
disconnecting or swapping anything. In your case, voltage on purple
wire (power supply to motherboard) would be measured and number
reported. Then voltages on green and gray wires measured before and
when power switch is pressed. Finally voltages on any one red, orange,
and yellow wire measured as power switch is pressed. Useful data
collected in less than two minutes - and without endangering
reliability of a second computer.

Give up and you have learned nothing. Get a meter - a tool so
ubiquitous as to even sell in Sears, Home Depot, Lowes, Radio Shack,
and K-mart - to learn how a computer 'power supply system' works and to
know how to fix it both quickly and a first time.

 

[vaio]

Just to thank you all for the hints, you have been so gentle and
helpful. Bye.