Computer not working: nothing shows on monitor

[Phil Weldon]

'Dave' wrote:
| Holy crap, this is the longest thread I've seen where nobody has the right
| answer for the OP. Simply, replace the bad power supply. The mainboard
is
| not receiving a power_OK signal, and so it never starts. That's because
the
| power is NOT OK.
_____

Read twice, post once.
There is no possible way to reach your conclusion from the information given
by the original poster. Your diagnosis is wrong. If a 'power good' level
is not provided, the power supply shuts down. Also, the MOTHERBOARD
supplies the 'power good' level, unlike your belief that "The mainboard is
not receiving a power_OK signal." The original poster reports "The lights
come on, fans, drives spin up, usb devices get power, everything is normal,
except that my monitor stays black."

Phil Weldon

|
| | > Ok, so I have a custom built computer that has always worked great
| > until today. Problem description is below. Here are the specs:
| > AMD Athlon 64 3700+
| > Asus A8N-SLI
| > Nvidia 6800GS
| > 1GB (2x512) DDR400
| > 2 internal Maxtor SATA drives (200GB+250GB), 1 external Maxtor USB
| > drive (250GB)
| > 500w or 550w (can't remember) UltraXConnect modular PSU
| >
| > I will preface this with a couple points:
| > - I have not made any recent hardware changes
| > - I have not made any recent software changes
| > - The last week or two, on occasion, my computer just turned off, but I
| > dismissed this as nothing
| > So I get home today, and I turn on my computer. The lights come on,
| > fans, drives spin up, usb devices get power, everything is normal,
| > except that my monitor stays black. I restart the computer, same thing
| > happens. I try disconnecting and reconnecting the VGA cord, nothing. I
| > use a DVI-VGA adapter and still nothing. I try removing my graphics
| > card and re-socketing it, nothing!!
| >
| > Believing it may be a PSU problem (too much power being used), I
| > disconnect my internal CD drive and another 4-pin molex that I used for
| > some lights, nothing helped. I replug all power cables, still nothing.
| >
| > I am really aggravated. It sounds like it could be one of three things,
| > but I am also looking for suggestions as to other causes.
| > 1. A graphics card hardware problem
| > 2. A motherboard problem; PCI express socket maybe shorted out
| > 3. A PSU problem of some kind
| >
| > I do not have another pci-e card I can use to test the first two, so I
| > will ask friends for one to use, but this may take a very long time or
| > they may not have one. I am dependent on my computer for many things I
| > do. I really need help on this one, and I really appreciate it.
| >
|
You had a warning that this would happen, as your system
| started intermittently shutting down. Well-made power supplies will do
that
| when the voltages start drifting out of spec.
|
| Note that a power supply can be bad and still allow certain components to
| run. -Dave
|
|

 

[Rod Speed]

'Dave' wrote

Read twice, post once.

Understand the basics.

There is no possible way to reach your conclusion from the
information given by the original poster. Your diagnosis is wrong.
If a 'power good' level is not provided, the power supply shuts down.
Also, the MOTHERBOARD supplies the 'power good' level,

No it doesnt.

unlike your belief that "The mainboard is not receiving a power_OK signal."

He's right on that.
atx12vPSDGV1.pdf
3.3.1. PWR_OK

PWR_OK is a “power good” signal. It should be asserted high by the power supply to

indicate that the +12 VDC, +5VDC, and +3.3VDC outputs are above the undervoltage

thresholds listed in Section 3.2.1

 

[Phil Weldon]

'blacklotus90' wrote, in part:
| As far as a beeper, after reading the motherboard manual I found out
| there is no LED code, nor a beeper. It states that to hear warning
| beeps you have to have a speaker hooked up to 4 pins on the panel
| pin-set thing. I dug the speaker out of my Linux box, but it was a
| different connector format.
_____

Time to take a deep breath and slow down. What exact model of the A8N-SLI
do you have? There are three; A8N-SLI, A8N-SLI Deluxe, and A8N-SLI Premier.
The boards and manuals are different. If you need a speaker connection, you
only need to make two connections. A speaker connector to the motherboard
is a four position inline female header connector. Only the two end
positions are used. One connects to + 5 volts on the motherboard 'panel'
connector header pin and the other connects to the 'Speaker' motherboard
'panel' connector header pin. The two pins in between are not used. The
connection is not polarized (the connector can be turned 180 degrees and
still work correctly.) For any further diagnosis, other than installing
your display adapter in another system and finding it does not work, you
MUST connect a speaker. Though why the motherboard manufacturer did not
place a beeper onboard is beyond me... and given that omission, the system
assembler was very remiss in not connecting a chassis speaker.

At this point

* check the operation of the display adapter in another system
* attach a speaker to the 'panel' connector on the motherboard
* turn on the system without a display adapter and listen for beeps or
voice message (see my previous report)
* get help from a knowledgeable friend to do the above, if necessary
* use the services of a reputable computer repair shop or use in-warranty
repair if applicable (or just go directly to this step)

Finally, if you post again, be sure that you include ALL relevant
information about the behavior of your system before the failure and what
you have tried in diagnosing the problem. Do NOT forget details like the
EXACT model of the motherboard as you did in your posts. The only clue so
far is the quote from your manual, a passage that is not in the manual for
the A8N-SLI.

Phil Weldon



| >Normally when you press the power on, there will be a beep or two to
| >indicate the pc is starting up.
| >If you press the power, only light on, drive spin and no beep, then your
|
| As far as a beeper, after reading the motherboard manual I found out
| there is no LED code, nor a beeper. It states that to hear warning
| beeps you have to have a speaker hooked up to 4 pins on the panel
| pin-set thing. I dug the speaker out of my Linux box, but it was a
| different connector format.
|
| >install the video crad in the lower pci-e slot.
| >I had an A8N-sli that had the top pci-e slot die.
|
| Isn't that bad, I thought the mobo is made so that the second slot is
| for SLI cards only. Plus, if that is the case, I would still want a new
| motherboard.
|
| >Simply, replace the bad power supply. The mainboard is
| >not receiving a power_OK signal, and so it never starts. That's because
the
| >power is NOT OK.
|
| Unfortunately I cannot use the PSU from my linux box to test this, as
| it is only 200W. I may be able to borrow a PSU from a friend, though.
|
| >suspect you have overheated and FRIED something.
|
| Well, I doubt I fried anything, as I keep my PC on a surge protector. I
| never overclock, and I also keep a watch on system temps with my temp
| gauge and the sysfan utility. I have a whole bunch of fans in my case,
| so it is probably not caused by an overheat.
|
| >might be time to spend a few bucks adn get it checked by a PRO
|
| Yeah, I'm really close to calling in the 1 year onsite tech support
| that came with my compute, but it can be such a hassle, so I would love
| to solve this some better way.
|

 

[Phil Weldon]

'Rod Speed' wrote, in part:
| PWR_OK is a “power good” signal. It should be asserted high by the power
supply to
|
| indicate that the +12 VDC, +5VDC, and +3.3VDC outputs are above the
undervoltage
|
| thresholds listed in Section 3.2.1
_____

You are correct that the power supply provides the 'Power Good' signal to
indicate minimum voltage levels are being produced; I had it backwards.
Thank you for correcting my error.

But there is still no way to reach the conclusion that the power supply is
faulty given the information provided by the original poster, especially
with the added information by the original poster that there is no provision
in his system as it is to get a beep code or voice notification of POST
problems.

Phil Weldon

| > 'Dave' wrote
|
| >> Holy crap, this is the longest thread I've seen where nobody has
| >> the right answer for the OP. Simply, replace the bad power supply.
| >> The mainboard is not receiving a power_OK signal, and so it never
| >> starts. That's because the power is NOT OK.
| > _____
|
| > Read twice, post once.
|
| Understand the basics.
|
| > There is no possible way to reach your conclusion from the
| > information given by the original poster. Your diagnosis is wrong.
| > If a 'power good' level is not provided, the power supply shuts down.
| > Also, the MOTHERBOARD supplies the 'power good' level,
|
| No it doesnt.
|
| > unlike your belief that "The mainboard is not receiving a power_OK
signal."
|
| He's right on that.
| atx12vPSDGV1.pdf
| 3.3.1. PWR_OK
|
| PWR_OK is a “power good” signal. It should be asserted high by the power
supply to
|
| indicate that the +12 VDC, +5VDC, and +3.3VDC outputs are above the
undervoltage
|
| thresholds listed in Section 3.2.1
|
|
| > The original poster reports "The lights come on, fans,
| > drives spin up, usb devices get power, everything is
| > normal, except that my monitor stays black."
|
|
| > | >>
| >> | >>> Ok, so I have a custom built computer that has always worked great
| >>> until today. Problem description is below. Here are the specs:
| >>> AMD Athlon 64 3700+
| >>> Asus A8N-SLI
| >>> Nvidia 6800GS
| >>> 1GB (2x512) DDR400
| >>> 2 internal Maxtor SATA drives (200GB+250GB), 1 external Maxtor USB
| >>> drive (250GB)
| >>> 500w or 550w (can't remember) UltraXConnect modular PSU
| >>>
| >>> I will preface this with a couple points:
| >>> - I have not made any recent hardware changes
| >>> - I have not made any recent software changes
| >>> - The last week or two, on occasion, my computer just turned off,
| >>> but I dismissed this as nothing
| >>> So I get home today, and I turn on my computer. The lights come on,
| >>> fans, drives spin up, usb devices get power, everything is normal,
| >>> except that my monitor stays black. I restart the computer, same
| >>> thing happens. I try disconnecting and reconnecting the VGA cord,
| >>> nothing. I use a DVI-VGA adapter and still nothing. I try removing
| >>> my graphics card and re-socketing it, nothing!!
| >>>
| >>> Believing it may be a PSU problem (too much power being used), I
| >>> disconnect my internal CD drive and another 4-pin molex that I used
| >>> for some lights, nothing helped. I replug all power cables, still
| >>> nothing.
| >>>
| >>> I am really aggravated. It sounds like it could be one of three
| >>> things, but I am also looking for suggestions as to other causes.
| >>> 1. A graphics card hardware problem
| >>> 2. A motherboard problem; PCI express socket maybe shorted out
| >>> 3. A PSU problem of some kind
| >>>
| >>> I do not have another pci-e card I can use to test the first two,
| >>> so I will ask friends for one to use, but this may take a very long
| >>> time or they may not have one. I am dependent on my computer for
| >>> many things I do. I really need help on this one, and I really
| >>> appreciate it.
| >>>
| >>
| > You had a warning that this would happen, as your system
| >> started intermittently shutting down. Well-made power supplies will
| >> do that when the voltages start drifting out of spec.
| >>
| >> Note that a power supply can be bad and still allow certain
| >> components to run. -Dave
|
|

 

[Rod Speed]

Rod Speed wrote

You are correct that the power supply provides the 'Power Good'
signal to indicate minimum voltage levels are being produced;
I had it backwards. Thank you for correcting my error.

But there is still no way to reach the conclusion that the power
supply is faulty given the information provided by the original poster,

I didnt comment on that.

What you say is arguable tho, particularly if the video card
isnt getting the 12V it needs anymore for whatever reason.

especially with the added information by the original
poster that there is no provision in his system as it is to
get a beep code or voice notification of POST problems.

Sure, but thats a different matter to where the problem can be.

 

[beerspill]

Well, I doubt I fried anything, as I keep my PC on a surge protector.

That's like saying you don't get into accidents because you have car
insurance..

You don't need a surge through the AC lines to fry something. A surge
can do damage if you plug in a connector or card the wrong way, short
the motherboard to the case, zap a part with static electricity during
handling (doesn't require a noticeable spark), or plug or unplug a
cable while either the computer or device is powered on (hot pluggable
devices, like SATA drives and USB accessories, are suposed to be
exceptions, but even they can suffer from a current surge during
plug-in).

The beep codes given by the speaker are so important that you should
install one. Many speaker connectors are made to be disassembled. See
here:

www.usbman.com/Guides/BelkinMotherboard_cable_assembly.htm

While those illustrated instructions are for a USB cable, speaker
cables are ofte similar, except for the number and locations of the
pins.

Try removing all cards and disconnecting all drives (hard, optical) to
lessen the load on the power supply. Be sure to handle and store those
cards using proper anti-static techniques - search for "ESD
precautions" and follow the recommendations.

I'm really close to calling in the 1 year onsite tech support
that came with my compute, but it can be such a hassle, so I would love
to solve this some better way.

How's that better way going so far?

 

[Phil Weldon]

'Rod Speed'
| I didnt comment on that.
|
| What you say is arguable tho, particularly if the video card
| isnt getting the 12V it needs anymore for whatever reason.
_____

I realize you did not comment on what the problem could be, but now that you
have: without any POST problem information, the problem can not be
definitively assigned to the power supply, no matter how the 'Power Good'
signal operates, unless the power supply tests bad.

Phil Weldon

| > Rod Speed wrote
|
| >> PWR_OK is a “power good” signal. It should be asserted
| >> high by the power supply to indicate that the +12 VDC,
| >> +5VDC, and +3.3VDC outputs are above the undervoltage
| >> thresholds listed in Section 3.2.1
|
| > You are correct that the power supply provides the 'Power Good'
| > signal to indicate minimum voltage levels are being produced;
| > I had it backwards. Thank you for correcting my error.
|
| > But there is still no way to reach the conclusion that the power
| > supply is faulty given the information provided by the original poster,
|
| I didnt comment on that.
|
| What you say is arguable tho, particularly if the video card
| isnt getting the 12V it needs anymore for whatever reason.
|
| > especially with the added information by the original
| > poster that there is no provision in his system as it is to
| > get a beep code or voice notification of POST problems.
|
| Sure, but thats a different matter to where the problem can be.
|
|
| >>> 'Dave' wrote
|
| >>>> Holy crap, this is the longest thread I've seen where nobody has
| >>>> the right answer for the OP. Simply, replace the bad power supply.
| >>>> The mainboard is not receiving a power_OK signal, and so it never
| >>>> starts. That's because the power is NOT OK.
| >>> _____
| >>
| >>> Read twice, post once.
| >>
| >> Understand the basics.
| >>
| >>> There is no possible way to reach your conclusion from the
| >>> information given by the original poster. Your diagnosis is wrong.
| >>> If a 'power good' level is not provided, the power supply shuts
| >>> down. Also, the MOTHERBOARD supplies the 'power good' level,
| >>
| >> No it doesnt.
| >>
| >>> unlike your belief that "The mainboard is not receiving a power_OK
| >>> signal."
| >>
| >> He's right on that.
| >> atx12vPSDGV1.pdf
| >> 3.3.1. PWR_OK
| >>
| >> PWR_OK is a “power good” signal. It should be asserted high by the
| >> power supply to
| >>
| >> indicate that the +12 VDC, +5VDC, and +3.3VDC outputs are above the
| >> undervoltage
| >>
| >> thresholds listed in Section 3.2.1
| >>
| >>
| >>> The original poster reports "The lights come on, fans,
| >>> drives spin up, usb devices get power, everything is
| >>> normal, except that my monitor stays black."
| >>
| >>
| >>> | >>>>
| >>>> | >>>>> Ok, so I have a custom built computer that has always worked great
| >>>>> until today. Problem description is below. Here are the specs:
| >>>>> AMD Athlon 64 3700+
| >>>>> Asus A8N-SLI
| >>>>> Nvidia 6800GS
| >>>>> 1GB (2x512) DDR400
| >>>>> 2 internal Maxtor SATA drives (200GB+250GB), 1 external Maxtor USB
| >>>>> drive (250GB)
| >>>>> 500w or 550w (can't remember) UltraXConnect modular PSU
| >>>>>
| >>>>> I will preface this with a couple points:
| >>>>> - I have not made any recent hardware changes
| >>>>> - I have not made any recent software changes
| >>>>> - The last week or two, on occasion, my computer just turned off,
| >>>>> but I dismissed this as nothing
| >>>>> So I get home today, and I turn on my computer. The lights come
| >>>>> on, fans, drives spin up, usb devices get power, everything is
| >>>>> normal, except that my monitor stays black. I restart the
| >>>>> computer, same thing happens. I try disconnecting and
| >>>>> reconnecting the VGA cord, nothing. I use a DVI-VGA adapter and
| >>>>> still nothing. I try removing my graphics card and re-socketing
| >>>>> it, nothing!!
| >>>>>
| >>>>> Believing it may be a PSU problem (too much power being used), I
| >>>>> disconnect my internal CD drive and another 4-pin molex that I
| >>>>> used for some lights, nothing helped. I replug all power cables,
| >>>>> still nothing.
| >>>>>
| >>>>> I am really aggravated. It sounds like it could be one of three
| >>>>> things, but I am also looking for suggestions as to other causes.
| >>>>> 1. A graphics card hardware problem
| >>>>> 2. A motherboard problem; PCI express socket maybe shorted out
| >>>>> 3. A PSU problem of some kind
| >>>>>
| >>>>> I do not have another pci-e card I can use to test the first two,
| >>>>> so I will ask friends for one to use, but this may take a very
| >>>>> long time or they may not have one. I am dependent on my computer
| >>>>> for many things I do. I really need help on this one, and I really
| >>>>> appreciate it.
| >>>>>
| >>>>
| >>> You had a warning that this would happen, as your system
| >>>> started intermittently shutting down. Well-made power supplies
| >>>> will do that when the voltages start drifting out of spec.
| >>>>
| >>>> Note that a power supply can be bad and still allow certain
| >>>> components to run. -Dave
|
|

 

[Rod Speed]

Rod Speed wrote _____

I realize you did not comment on what the problem could be, but now
that you have: without any POST problem information, the problem can
not be definitively assigned to the power supply, no matter how the
'Power Good' signal operates, unless the power supply tests bad.

Yes, but the POST beeps etc wont necessarily indicate that
particular problem, its better to check that possibility in other ways.

 

[Dave]

Phil - Let experience step in. Sudden shutdowns are sometimes a bad
mainboard or other components, but almost always a bad power supply. Power
supplies have various failure modes ranging from intermittent low voltage
causing lockups to Mt. St. Helens (yes, I've seen that one). Of all the
power supplies I've seen fail, probably 50% of them display the exact
symptoms that the OP wrote about. That is, there comes a time when fans
spin up, hard drives spin up, LEDs come on, but mainboard never POSTS.

I could be wrong, but if it was a system I was responsible for, and given
ONLY the information written in the OP, I would tell my tech to replace the
power supply and be shocked if that did not solve the problem. -Dave

 

[Phil Weldon]

'Dave' wrote:
| Phil - Let experience step in. Sudden shutdowns are sometimes a bad
| mainboard or other components, but almost always a bad power supply.
Power
| supplies have various failure modes ranging from intermittent low voltage
| causing lockups to Mt. St. Helens (yes, I've seen that one). Of all the
| power supplies I've seen fail, probably 50% of them display the exact
| symptoms that the OP wrote about. That is, there comes a time when fans
| spin up, hard drives spin up, LEDs come on, but mainboard never POSTS.
|
| I could be wrong, but if it was a system I was responsible for, and given
| ONLY the information written in the OP, I would tell my tech to replace
the
| power supply and be shocked if that did not solve the problem. -Dave
_____

Why suggest a solution which may not correct the problem? Especially when
diagnostic information is readily available? The original poster is
flailing for a solution without knowing how to diagnose the problem. Your
suggestion is of the same order. Whatever experience you may have, it
evidently does not apply here.

Phil Weldon

| Phil - Let experience step in. Sudden shutdowns are sometimes a bad
| mainboard or other components, but almost always a bad power supply.
Power
| supplies have various failure modes ranging from intermittent low voltage
| causing lockups to Mt. St. Helens (yes, I've seen that one). Of all the
| power supplies I've seen fail, probably 50% of them display the exact
| symptoms that the OP wrote about. That is, there comes a time when fans
| spin up, hard drives spin up, LEDs come on, but mainboard never POSTS.
|
| I could be wrong, but if it was a system I was responsible for, and given
| ONLY the information written in the OP, I would tell my tech to replace
the
| power supply and be shocked if that did not solve the problem. -Dave
|
|

 

[Rod Speed]

Dave wrote

Why suggest a solution which may not correct the problem?

Because it usually is what produces the symptoms seen.

Especially when diagnostic information is readily available?

That may not help if the problem is that the
video card isnt getting enough 12V power.

The original poster is flailing for a solution
without knowing how to diagnose the problem.

Yes, but as Dave says, the power supply is
usually what produces the symptoms seen.

Your suggestion is of the same order.

Nope, nothing like it.

Whatever experience you may have, it evidently does not apply here.

Corse it does.

 

[davsf]

I have a similar problem - my PC has trouble starting up the monitor.
It is intermittent, and it sometimes requires 50 to 100 "switch
off/switch on/power on" sequences before it will finally light up the
monitor. I *thought* it was the video card and tried a different one -
no change. I followed the advice given here and took everything out
including the video card and listened to see if there were any beeps -
none. I then re-inserted the video card and kept trying and the
monitor finally came on. But I booted from a diskette (win98 startup)
because I didn't have my other two cards installed (sound and extra
USB2 addon).

Since I am not getting any beeps, does that mean my power supply is
probably going bad intermittently? How do I check to make sure the
little case speaker is wired up correctly? I followed the manual
diagram, but, since I don't hear any beeps I wonder if I got it right?
Is there a DOS command that will cause that little speaker to make a
noise? I would like to do that while I have it up in DOS, just to MAKE
SURE my speaker is working. If I restart so I can go to windows it
will take another long time to get it back up again.

I have a Supermicro P6SBA (the higher-end 440BX that went to 1 ghz for
a PIII). I used a 350 watt power supply (FSP brand) and I haven't had
any problems with this PC for at least 4 years now. Is there a way to
find out whether or not the power supply is the problem (it NEVER quits
after it gets powered up and lights up the monitor - only gives a lot
of trouble lighting up the monitor on power up).

By the way, I only paid about $150 for this motherboard back there
about 5 years ago, and now I see someone on EBAY selling the same thing
for $350 - are they crazy? This is old obsolete stuff! What am I
missing here?

Any advice on helping me pin down exactly why my monitor takes so many
attempts to light up - I'd appreciate it (I have tried different
monitors, of course - same thing).

littleberry

 

[ChrisH]

I've had a few machines exhibit these symptoms (no post, black screen,
fans/disks spin - still shuts off using 4sec hold on the power
switch), only resolved one of them - and that was a partially unseated
CPU. Took it out and reseated and it was OK again. Prior to that I'd
replaced PSU, graphics - in fact everything removable bar the CPU.

Currently still have a P4T533-C which behaves like it doesn't have a
BIOS chip installed - same symptoms. Can't be arsed buying a
replacement chip on the off chance, but might try hot flashing
existing chip in another board (don't have another P4T533-C though,
but might be able to force it using a P4S800D-E I have lying around).

 

[davsf]

Well, I just tried my P6SBA out with a different power supply and it
didn't work either. I am dismayed! I really thought that it would be
the power supply causing the monitor not to light up, but, this other
power supply (from a different good working PC) didn't make any
difference.

I am starting to think it is the motherboard since I don't hear any
beeps at all. Everything seems to power up (hard drives, cdrom,
floppy, fans, etc), but, the monitor just doesn't lite up. When in
this dark state, I can even see the HD start to be accessed like it
trying to start windows, but, NO MONITOR (I tried using different
cables, different monitors, and different video cards - all the same).
I can even use the push-method on the power switch to shut it down, so,
at least that part of the motherboard is working. I have to keep
switching off/switching on/powering on many many times (around 100) and
then, sudeenly the monitor lights up. If I keep the PC running then it
just does fine, but if I reset or power down for any reason, I have to
go throught that sequence again.

WHAT COULD IT BE?

I hate to just throw this maching away - it is working fine once it
gets up - and it has a whole lot of things on it that are important for
various things. Any ideas - at all?

 

[Keith]

Well, I just tried my P6SBA out with a different power supply and it
didn't work either. I am dismayed! I really thought that it would be
the power supply causing the monitor not to light up, but, this other
power supply (from a different good working PC) didn't make any
difference.

I am starting to think it is the motherboard since I don't hear any
beeps at all. Everything seems to power up (hard drives, cdrom,
floppy, fans, etc), but, the monitor just doesn't lite up. When in
this dark state, I can even see the HD start to be accessed like it
trying to start windows, but, NO MONITOR (I tried using different
cables, different monitors, and different video cards - all the same).
I can even use the push-method on the power switch to shut it down, so,
at least that part of the motherboard is working. I have to keep
switching off/switching on/powering on many many times (around 100) and
then, sudeenly the monitor lights up. If I keep the PC running then it
just does fine, but if I reset or power down for any reason, I have to
go throught that sequence again.

WHAT COULD IT BE?

I hate to just throw this maching away - it is working fine once it
gets up - and it has a whole lot of things on it that are important for
various things. Any ideas - at all?

Give the monitor a bloody good hiding , worked on my old tv.

 

[Dave]

Why suggest a solution which may not correct the problem? Especially when
diagnostic information is readily available?

If the system won't run POST, there is no diagnostic information available.

The original poster is
flailing for a solution without knowing how to diagnose the problem. Your
suggestion is of the same order. Whatever experience you may have, it
evidently does not apply here.

Well, that depends. The OP can spend lots of time fiddling around with
various suggestions that probably won't work, or he can replace the power
supply. If he does, there is at least a 99.9% chance that the problem will
be corrected. It's a good idea to keep a spare power supply on hand anyway.

You can shotgun this with the OP all you want to. I prefer to follow the
symptoms and just get the thing repaired already, with a minimum of muss and
fuss. We're both trying to be helpful, in our own way. You can suggest
other things to check, and that's fine. I am TELLING the OP what the
solution is, providing a convenient short-cut. -Dave

 

[Dave]

Well, I just tried my P6SBA out with a different power supply and it
didn't work either. I am dismayed! I really thought that it would be
the power supply causing the monitor not to light up, but, this other
power supply (from a different good working PC) didn't make any
difference.

I am starting to think it is the motherboard since I don't hear any
beeps at all. Everything seems to power up (hard drives, cdrom,
floppy, fans, etc), but, the monitor just doesn't lite up. When in
this dark state, I can even see the HD start to be accessed like it
trying to start windows, but, NO MONITOR (I tried using different
cables, different monitors, and different video cards - all the same).
I can even use the push-method on the power switch to shut it down, so,
at least that part of the motherboard is working. I have to keep
switching off/switching on/powering on many many times (around 100) and
then, sudeenly the monitor lights up. If I keep the PC running then it
just does fine, but if I reset or power down for any reason, I have to
go throught that sequence again.

WHAT COULD IT BE?

I hate to just throw this maching away - it is working fine once it
gets up - and it has a whole lot of things on it that are important for
various things. Any ideas - at all?

Whoa, someone else jumped into the thread with the same problem with a
different PC? We need more information on this one. What was the exact
make/model of the original power supply, and what is the exact make/model of
the power supply that was just installed? -Dave

 

[Webusenet]

You know, it could be something very simple. Same thing just happened to me:
would not boot , blank screen: it was the CMOS battery.
(did notice computer was losing time prior to failure).

This can also happen if your CMOS settings get really screwed up. Reset
your CMOS while you have your battery out.

Hoot

 

[Webusenet]

I did not see reference to the chipset fan in any of the postings and, I
don't know if the systems described could be caused by it's failure, but in
the interest of leaving no turn unstoned....

Remember that some of the original A8N-SLI mobos (particularly, the Deluxe)
were shipped with a faulty chip set fan which would fail prematurely. I
have replaced 2 (replacement fan provided by ASUS free of charge).

Did you check that your chip set fan is turning?

Hoot

 

[davsf]

My system is an older one - Supermicro P6SBA with a PIII (1 ghz SECC2).
The power supply is an FSP350-60PN, and the one I put in temporarily
to test it was an Antec 380. The Antec works in a different PC and it
is back in it now and working fine.

The CMOS battery idea appeals to me (simple, easy to fix), but, I just
don't understand why it would make the monitor just go blank on me. I
am going to check that out - I hadn't noticed if the clock was slipping
before all this started, so I guess I should just remove the battery (a
small silver round thingie - right?) and then hit the right jumper to
"reset CMOS" - right? I will have to go back to the manual and see
which jumper to short for that - I'll get back with whatever I find
out. I sure hope it is the CMOS battery, that would be a lifesaver
here - this old PC has been a real workhorse and I would just hate to
have to ditch it. Especially since I see an EBAY ad selling this same
motherboard for $350 (crazy, no?).
littleberry