[dundee] Hardware for a firewall/content filter

[Robert Ladyman]

> On Mon, 23 May 2011 10:21 +0100, "Robert Ladyman" <it at file-away.co.uk>
> 
> wrote:
> > The simplest way is just any old unwanted PC with two network cards
> > (even an old portable) and IPCOP.
> 
> Using old hardware for something that'll be on all the time can actually
> work out more expensive than buying a new low power system.
> 
> The electricity will cost somewhere around £1/(watt*year) (very roughly
> - electricity prices vary, ~11.4p/kWh comes out to £1/(watt year),
> adjust depending on how much you pay for electricity). A desktop will
> probably use somewhere between 50W and 500W, laptops are anywhere from
> 10W up (most of them are quite a lot above that - I wouldn't be
> surprised if the power brick on it's own manages to dissipate more than
> that for most laptops).
> 
> You can get energy meters that go between electrical devices and the
> wall socket and actually measure the power usage. I have one that I'd be
> happy to lend to anyone wanting to do some measuring (if I can remember
> where it is).
> 
> If you are using a desktop machine for this type of thing it's worth
> having a look to see what you can do to save power. Disconnecting a
> graphics card could save 100W or so, the fans are probably using a few
> 10s of W so make sure they're on temperature dependent and see what you
> can do to improve the passive cooling, make sure the CPU is using
> frequency scaling if it supports it, make sure hard drives are spinning
> down when they can. The PSU will be dissipating anywhere between 5% and
> 50% of the computers power usage - there's not much you can do about one
> you've already got but do check efficiency ratings on any new ones.
> 
> The environmental impact rather than just the cost to you is a lot more
> complicated and might push things towards keeping the old hardware
> (though minimising it's power usage is a plus for both reasons).
> 
> Robert
> ________________________________________________________
> Robert McWilliam     rmcw at allmail.net    www.ormiret.com
> 
> The opinions expressed herin are not necessarily those of my
> employer, not necessarily mine, and probably not necessary.

Don't forget that you have to subtract the heat output from your heating 
budget accordingly, and in Scotland that will mean that, other than at the 
peak of summer, the net gain or loss will be nil. 

-- 
Robert Ladyman
File-Away Limited
3 Ralston Business Centre, Newtyle, Blairgowrie
Perthshire  PH12 8TL SCOTLAND
Tel: +44 (0) 1828 898 158
Mobile: +44 (0) 7732 771 649
http://www.file-away.co.uk

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