[dundee] Hardware for a firewall/content filter

[Robert McWilliam]

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.