[LINK] Leave on, or turn off?

[Saliya Wimalaratne]

On Thu, Nov 30, 2006 at 11:22:35AM +1100, Stewart Fist wrote:
> Has anyone got a reference to a real bit of reliable research which says
> whether it is better to turn a computer off at night, or leave it on 24/7
> (disregarding energy consumption) ?

I have some personal (non-necessarily-anecdotal :) experience:

If computers are in clean, air-conditioned comfort and on true UPS, 
they can last for a *very long time* (think > 8 years) with no problems.
This is on 24/7. Some of these computers are PCs old enough to have
mechanical power switches.

In the home, things are different: 
* not clean
* not temp-controlled
* not true UPS

for the majority of people. UPS is a big factor - power coming
from your grid isn't clean, and computers like it clean (though
new power supplies mean they are better able to handle dirtier
power now than they were). The surge-protection abilities of 
real UPS also need to be considered, as surges destroy lots of
electronic equipment every year.

Way back in the days of AT power supplies, turning computers on
was a 'shock' to the system - an electric surge created when the
physical contacts were bridged at the power button on the case.
Things failed, often, at this turn-on spike. But this spike is
much less offensive with modern power supplies/computers.

You also have 'thermal shock' - components that are on heat up,
components that are off don't. Switching between one and the
other results in expansion/contraction of hardware... this happens
even with today's switching power supplies.

Today, computer OSs and BIOSes can spin down components that
aren't used, resulting in very low power consumption while
still being "on". 

For an average person with no real environmental control, and
a non-mechanical off/on switch, I would suggest 'leave off when
not in use'... 

Regards,

Saliya