When my desktop PC is idle for a time, it shuts off. At first, I thought it
was a thermal issue, but the unit doesn’t shut off when it’s being used, even
for extended periods. That led me to think it was a power-management glitch. I
figured that disabling system standby and/or hibernation would work around the
problem, but when I checked the settings, they were already turned off.
I don’t have anything very specific, but there are a few things I’ll throw
out as places to look and perhaps some items that hadn’t been thought of
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The first thing that comes to mind is your screen saver. Particularly if
“after a time” is a relatively consistent amount of time. Normally a screen
saver wouldn’t turn the computer off, but a screen saver is software after all,
and could have a bug that’s manifesting on your machine.
This certainly sounds and feels like it could be a standby or hibernation
issue – though if either you’d be able to tell right away when you turn the
computer back on. If it resumes immediately it went into standby, and if it
says “resuming from hibernation” that’s pretty clear. Even if hibernation and
standby are turned off, for a long time I ran into a problem where they would
automagically turn themselves back on.
Another place to look is the ACPI (Advanced Configuration and Power
Interface) power settings in the BIOS. Power management is, at its root, a BIOS
initiated and managed thing. Perhaps turning that functionality off in the
BIOS, or at least twiddling with the settings there might affect the issue.
There are services that kick in after inactivity. The indexing service is
one (you can turn it off), and in Vista I believe there’s a bunch of defragging
stuff that happens in the background after some idle time. In either of these
or similar cases it’s possible that the service is causing a problem that would
result in the machine shutting down.
In fact, because of the possibility of services kicking in at idle time, it
actually still could be a thermal issue. The services might be driving the
machine harder than you do when you use it normally, and thus the machine might
be experiencing higher temperatures. If it’s something you can watch, try
running process explorer and see if
some application is using up all CPU prior to the machine shutting down.
It certainly wouldn’t hurt to run a RAM
You might have a look in the event log for anything suspicious. Error
messages or messages of other activity that happen around the time of the
shutdown might throw some interesting light on the situation.