[LINK] Leave on, or turn off?

Adam Todd link at todd.inoz.com
Thu Nov 30 16:02:37 AEDT 2006


At 11:22 AM 30/11/2006, 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 guess the question resolves into
>a) the electronics, and
>b) hard-disk-bearing wear.
>
>I've got plenty of so-called 'expert' opinion (mostly in favour of leaving
>computers on), but this seems essentially to be anecdotal only.

I can only give and expert and professional opinion from 20 years of research!

In the days of the washing machine disk drives, leaving them on was imperative.

In the days of Miniscribe 20 MB hard drives (MFM or RLL) leaving them on 
was OK, provided you didn't let them get too hot for too long as the 
bearings dried out.

Now the real test.  I have a lot of old Seagate 100 MB IDE drives.  Some 
were in workstations that were turned on and off a lot.  All died within a 
few years.

The other 15 odd are in my servers and have been in service since the early 
1990s and continue to run.  Only two have crashed in the last three 
years.  The rest continue to operate, except NS2 which was shut down 
recently, but the drive still works!  These drives would have had maybe 16 
restarts in the period of deployment.

Switch mode power supplies run better left on.  Each time you fire them up 
they have to sync and oscillate which places enormous strain on the 
components.  Most PSU's will die from over heating because gunk builds up 
causing the fans to fail and go unnoticed.  I use a blow and suck method to 
clean operational fans and give all fans and PSUs a clean out annual or on 
the next power fail occasion.  I've only had a few PSU's die in the last 
three years from excessive switching on and off.  (Well ok, three power 
fails in 2 days without a UPS.  But the PSU's were dated 1992 :) )

Monitors are different.  If they have a standby mode then use it over power 
right down.  (Unless you don't intend to use the monitor for a more than a 
few days.)  CRT monitors generate a lot of startup noise and use a lot of 
power on activation.  They are best left idle as the consumption of power 
alone (even though that was not a factor of your request) is huge every 
time you power them on.  In idle they keep a very low flow of voltage 
making the startup a lot more pleasant and a lot less strain on the components.

LCDs.  TURN THEM OFF!  It at least put them into sleep.  The tubes that do 
the backlight have a very limited life.  Don't leave them on running screen 
saves, this really reduces lifetime of your tubes.  Same with laptops, set 
your lid switch to either ignore or standby and close your lid.  Save your 
tubes.  It's a really expensive money and time cost to replace dead 
tubes.  They do DIE.

Watch our for PLug Packs on ANY EQUIPMENT.  If you can, buy a professional 
switch mode power supply that delivers a range of voltages and connect all 
your Plug Pack equipment to that PSU.  Wall Plug Packs aren't designed for 
being left in and on.  They get hot, generate incredible magnetic fields 
(except the switch mode ones you sometimes find with mobile phones and rare 
other equipment, if it's really feather light, it's switch, if it has any 
weight, it's inductive.)

You will also find that using a single Switch mode power supply is far 
cheaper on your bill than 10 or 15 plug packs.

12 volts and 5 Volts are common for a lot of equipment.  You can use a 
standard Computer power supply quite happily, just get a good one.  With 12 
and 5 volts you can also use solar power and batteries to power all your 
equipment.

Some laptops use greater than 12 volts, (most) but you can get 12 volt up 
converters.

Equipment running on 7.5 and 9 volts can sometimes take a 12 volt input 
feed because they have voltage regulators and converters internally.  Don't 
assume this however, check the circuits or find out.  I have a lot of gear 
rated for 9 volts that are actually 5 volt circuits.  They down the 9 volts 
to 5 volts, the extra volts on the input helps increase the power output of 
the converter and hence they boxes can do more.  A 9 volt supply is also 
cheaper than a 5 volt one :)  Remembering you need a 3 volt drop for 
regulators.

Any plug packs delivering AC rather than DC are more than likely doing 
their own PSU integrally.  You can pretty much deliver anything up to 
around 40 volts AC to these without problems.  But check. and Recheck.

I use a lot of solar power for modern technology, it's cheap (very) and 
there all day and night (well the bats are!)

On on the FANS topic, check your CPU fans every six months.  REALLY.  Those 
cruddy cheap fans they stick on most CPUs gunk up really fast and then 
you'll start getting intermittent freezes - even for a fraction of a 
second, you might think it's just windows (etc) pausing for a breath, but 
more often then not, it's the CPU over heating.

Laptops are notorious for over heating.  Hence the reason they are NOT sold 
as laptops but notebooks.  The fans generally get blocked by your thigh if 
you place them on your leg.  RTFM - the first few pages of any manual tell 
you to avoid this kind of operation.  (Good in winter though!)

Laptops are designed to be turned on and off and their PSU's are very well 
designed.  Although mine is on most of the time I either hibernate it when 
it's not going to be used and on battery for more than 30 minutes, or if 
I'm walking around and opening and closing, standby is best.

Although it only takes 45 seconds to return from hibernation.
















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