The computer runs fine for a while.
 
The all of a sudden the screen just goes blank. Monitor light is still on. PSU fan is still blowing. Fans are still blowing on the MB.
 
It's an integrated vid card.
 
The whole system is 8 years old. They turn it off every night but they run it all day long (retired couple). Games, email, ebay. Nothing taxing.
 
I took the hard drive home and I'm attempting to clone it. Actually, backing it up first (Acronis 2015) and then I'll restore it to a new hard drive.
 
I have a new PSU just in case and I do have a spare vid card if necessary. 
 
The OS is Vista business (as I said, it's 8 years old).
 
Thoughts on the black out?

easy.  CPU is overheating.  
can happen even if it appears fan is working correctly.
download speedfan if you want to check the CPU temp before doing anything about it.
 
http://www.almico.com/speedfan.php

FYI... nothing about their room temp has changed.
 
So is it possible that the CPU fan (which was running when the black out occurred) is no longer powerful enough or has become "unseated" (i.e. CPU thermal grease dried out and needs to be replaced)?
 

If the CPU is overheating, the machine would likely not just "black out".
It would likely BSOD and reboot.  (I doubt less tech savvy users would disable the Automatic Restart.)
 
Most likely not the PS.
 
Does the system boot/run and display fine in Safe Mode?
Boot into Safe Mode... and let it stay in Safe Mode for an extended period.
If all is fine, it's most likely a config issue.
 
When the screen goes black, what happens if you tap the power button (not holding it in for four seconds).
If the machine gracefully shuts down, that tells you it was still within Windows... and had not crashed.
The display (alone) had blacked out.
That would put the issue on the onboard video or config/drivers.
If onboard video is the only defective culprit, the dedicated video card should resolve the problem.

Thanks Jim (and Beagle).
 
I'll investigate a little further tomorrow when I go back there.
 

 
 
How long does the screen work for. Whatever that time is ... that is how much time they get to email something or buy something for amazon. 
 
I could see this kind of game becoming an Olympic sport. 
 
 
If you can't fix it buy them a new one for Christmas  $279 right here  http://www.bestbuy.com/si...165000.p?skuId=5165000

Mooch Who Just Do Stuff.
 
 
You quack me up.

Good luck Ed!  Tomorrow I have to go to a client whose laptop "tried" to get the Windows 10 Anniversary update over the weekend and now only gets to the little dots spinning before rebooting (even in safe mode with networking).
 
I'm not optimistic 'cause my OWN windows 10 machine did the reboot cycle over the weekend as well (also trying to install v1607) and finally reverted back to the state before attempting the updates.
 
The most likely path for the client's laptop will be to pull the hard drive, get what data I can off of it, then "factory" the laptop and put the data back on - yay...

I REALLY hate to disagree with Jim, but I have seen this happen on two different systems.  both times the system would shut down without warning, just "go blank" after reaching a certain temperature and that didn't take long.
 
In both cases, the system would do exactly as you described.  the screen would go blank, the fans would all still be running, no beeps or anything from the computer.
 
running the speedfan program showed me that the temp was shooting up right before the fault.  checking the fault logs of windows confirmed that the system was having faults (can't remember the exact report)
 
both computers I removed the cpu fan, cleaned the thermal grease off of the cpu, replaced the fan with a new one using new thermal grease and everything worked like a charm.
 
I also then downloaded a cpu stress load tester and ran them all day after replacing the fan and verified that the temps would not increase too much to shut the system down.
 
I'm not saying this is going to be exactly the problem with this system and again, I really hate disagreeing with Jim because he's always spot on, but I HAVE seen this happen with overtemps.