> >FWIW, my primary desktop just needed a new power supply.  A transistor
blew
> >after 5+ years of being on almost continuously.  Anybody out there ever
> >hear of "inrush current" and the damage it does?!?!?!
>
> Almost every switch mode supply I've seen use Barium Titanate inrush
> current limiters - these are great devices - we used them on the output
> of a handheld inverter they protected the transistors very well indeed.
>
> I still would not ever leave a switchmode supply unattended - especially
> knowing that even switchmode transistors are susceptible to static
> damage during assembly and you never know when a fire could be caused.
>
> So if I wished to have a PC in a unattended environment I'd design my
> own supply with a heck of a lot of safeguards...
>
> Rgds
>
> mike
> Perth, Western Australia
> And others

I don't want to get into the OS system comparisons that some have been
making but I'm another who leaves a PC or 2 running continually. One has
now run for 4.5 years continuous (it acts as a facsimile receiver as well
as being used as a workhorse desktop) running Windows 3.1 with 8MB of RAM.
The power supply expired quietly after about 3.5 years and was swapped for
a new one. At the price (about $NZ40 including a case (approx $US23?) its
hardly worth repairing them. The biggest failure item I have seen is the
mains filter electrolytics which generally go out with a bang and split
longitudinally and blow their contents around the inside of the power
supply. As this country is universally 230 VAC and the supplies are usually
switchable 110 or 230 V ours are run in a different mode from most US ones.
On 110 AC the input electrolytics are run as a voltage doubler but on
230VAC they are simply placed in series across the rectified mains. I would
have thought that the voltage doubling mode would be harder on
electrolytics and lead to more failures. In my experience switching
transistor failures are less common. Even if a transistor does fail I think
it would be unusual for it to fail in such a way as to damage connected
equipment. of course, sudden loss of DC power can lead to damage or data
loss depending on configuration.

Regarding reliability of the system with time when run continually. I feel
that having the fax software in the background reduces the time the system
can be run before rebooting. Certainly, doing strange background tasks in
DOS can hasten the need for a reboot. Generally, a week is about the
longest I would expect to go before Windows started reporting low memory or
misbehaving. I have a log of startup times so I can check instantly how
long the system has been up. A Windows 95 machine (16MB RAM), which is not
running fax in the background, but which also runs continuously, seems more
stable than the 3.1 PC and much less prone to low memory messages after a
time so I suspect I could go several weeks at a time between reboots in
many cases. In practice I try to reboot every few days as I don't like to
risk losing a valuable work session on this PC due to unexpected problems.

No doubt some other OS's are much more stable but both of these systems
seem to be entirely adequate for practical purposes.