[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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