Charles said:
Regarding leaving equipment on all day:
One cannot generalise. It all depends on the equipment.
Tungsten filaments, as in a tungsten light bulb or the heater of a
fluoresccent lamp, do indeed cause a huge surge at switch-on.
However, as it is only for a fraction of a second you cannot see it
on a current meter. It is this surge that causes them to burn out
at switch- on.
Tungsten gives about 15 lumens per Watt. Fluorescent gives about 55.
It is better not to switch fluorescents on and off too often,
because whilst running they are so efficient that there is not much
saving.
Computers have hard drives. Sometimes, some background task makes
the motor run. Mechanical wear and tear has to be taken into
account.
Again, when a CPU is running, it gets warm. That is why they have a
fan fitted. If they are running for too long, the dopant on the chip
will shift, and the transistors that have been fabricated on the
chip may fail.
A server MUST be on 24/7 - but a domestic computer, used for just an
hour or so per day, is best left switched off.
I could say so much, after almost fifty years in engineering.
However, it is best to say that it depends on the individual case.
Not all servers *must* be on 24/7. Some people like to think so - but
realistically - most servers could blink on/off several times a day/night
and no one would likely ever notice. (Not saying that some servers have
applications running on them better served by long and relatively
uninterrupted up-time - but there are many types of servers that are one of
many redundant in a system and the individual outage would not affect
service to the customer as well as servers whose outages during certain
times would unlikely ever be noticed.)
Not all computers have moving parts. Even modern/fully functional Windows
XP/Vista machines used by everyday consumers may have few (a few fans) to no
moving parts. Hard Disk Drives are slowly giving way to solid-state drives.
In the end - it really comes down to what the end-user wants/needs and can
do over what may/may not happen with worn-out mechanical parts. Can the
end-user afford the electricity/bandwidth that may be used by their
'supposedly idle' PC? Is it green and does the end-user care? What sort of
machine is it, what does it do, why should/should not it be on 24/7?
On the moving parts going out - sometimes its more 'luck of the draw' other
than anything else. I have systems/components that have ran well for 15+
years (well meaning they did what originally intended) and I have had
systems/components that came to me dead (or died at the first power-cycle.)
