monitor image question

[ComputerSpaceFan]

Can anyone tell me other than a defective monitor or video card what
else might cause my computer screen to collapse?
I have had the same computer and monitor for a couple of years now
(both bought brand new) and they have worked fine until recently. Now
after a few hours the screen seems to bend over on itself along the top
edge and sometimes even collapses to a bright horizontal line only a
few pixels wide across the center of the monitor. If I move my mouse
around I can see it moving in the squished image.
If I turn the monitor off and on again the picture does not restore.
If I reboot the computer it's ok again for a little while but after an
hour or so it will collapse.
So obviously a defective monitor right? Wrong. I have connected it to
another computer and it works fine. (The other computer is a laptop but
has the same screen resolution)
So obviously a defective video card right? Wrong. I went and bought a
brand new video card for my system and the problem still occured.
Anyone got a clue what else might be going on here? My only guesses
left are either the powerbar / power cable or maybe the motherboard? I
doubt it's the motherboard because the video card is what drives the
monitor not the motherboard, right?
In case people need machine specs:
Intel Pentium 4 2.4GHz with 1024 megs of RAM running Windows XP Pro
(SP2)
Monitor is a NEC Multisync FE991sb
Video card(s) are both nVidia GE Force, the original being a FX 5600
and the new one being a 5500 OC with both the latest drivers and even
with the drivers packed with both cards.

I'm out of troubleshooting ideas at this stage.

 

[Ken]

Can anyone tell me other than a defective monitor or video card what
else might cause my computer screen to collapse?
I have had the same computer and monitor for a couple of years now
(both bought brand new) and they have worked fine until recently. Now
after a few hours the screen seems to bend over on itself along the top
edge and sometimes even collapses to a bright horizontal line only a
few pixels wide across the center of the monitor. If I move my mouse
around I can see it moving in the squished image.
If I turn the monitor off and on again the picture does not restore.
If I reboot the computer it's ok again for a little while but after an
hour or so it will collapse.
So obviously a defective monitor right?

Right! Almost certainly a poor solder connection associated with the
vertical deflection circuit. Such connections are subject to the
expansion that heat makes on the PWB or a vibration. Turning off the
monitor for a few moments may be enough to cause it to make connection
again. If you want to explore this theory, whack the side of the
monitor while it is failing. It might restore the vertical momentarily.

I guess it could also be a bad conductor in the video cable for the
vertical sync, but I would go with the solder connection particularly
since your monitor is a couple of years old.

Wrong. I have connected it to

 

[ComputerSpaceFan]

Thanks Ken, I'll have a look at the monitor again. So what you're
telling me is there is no way it could be the motherboard right? The
power bar or the power cable are easy things for me to replace but I'd
like to negate the motherboard if I possibly can.

 

[kony]

So obviously a defective monitor right? Wrong. I have connected it to
another computer and it works fine. (The other computer is a laptop but
has the same screen resolution)

Did you try same refresh rate?
You seem to be making sweeping assumptions without mention
of whether you actually reproduced same exact environment,
ONLY changing one variable.

So obviously a defective video card right? Wrong. I went and bought a
brand new video card for my system and the problem still occured.

Not only is an exact description of the problem important,
but also exact scenario in which it occurred, and exactly
what you had tried to resolve before changing physical
hardware. For example the screen refresh rate, bios agp
drive settings, checking the card's fan, power supply
voltages.

Anyone got a clue what else might be going on here? My only guesses
left are either the powerbar / power cable or maybe the motherboard? I
doubt it's the motherboard because the video card is what drives the
monitor not the motherboard, right?

Motherboard can make video card malfunction. That is not
necessarily a "defective" or "broken" motherboard though,
merely that one can effect the other in some way.

In case people need machine specs:
Intel Pentium 4 2.4GHz with 1024 megs of RAM running Windows XP Pro
(SP2)
Monitor is a NEC Multisync FE991sb
Video card(s) are both nVidia GE Force, the original being a FX 5600
and the new one being a 5500 OC with both the latest drivers and even
with the drivers packed with both cards.

I'm out of troubleshooting ideas at this stage.

It would be useful to try the video card, and monitor, with
another system at the same resolution and refresh rate.

Since we don't know if you exactly reproduced the resolution
and refresh rate with the laptop, it might be useful to
retry that. Often the kind of problem you describe is a
monitor fault, when the video card is working but producing
garbage output it is generally a different looking
corruption like random characters or blocks of colors, or a
kind of distorted contrast banding but not a deviation in
the full video "window" on the screen, it's size.

 

[ComputerSpaceFan]

Not to worry, Ken was right. I gave the monitor an almighty whack when
it went squishy and the picture came back so it must have been pure
luck that it didn't do it with the second computer.
Now at least I know what to fix.
Thanks all for the input!

 

[Ken]

Thanks Ken, I'll have a look at the monitor again. So what you're
telling me is there is no way it could be the motherboard right? The
power bar or the power cable are easy things for me to replace but I'd
like to negate the motherboard if I possibly can.

I learned a long time ago not to exclude an area just because of the
symptoms. That being said, it is unlikely to be the MB or the video
card. Far more likely to be the monitor. That is where I would look if
it were my problem.