On Tuesday 26 May 2009, Joseph Apuzzo wrote:
> No just wanted to do the routing on a Linux box, along with DHCP
> NTP and other services. I was going to keep the WRT56G to do all
> the wireless and such. Wanted to get full firewall and Web cache
> going to max out my Internet since my employer no longer pays for
> it.

That's all very do-able; if you're only looking for the router to take 
care of wired connections then it's a lot easier.

> Power is a point it will take more power but the equipment is free
> ( new power friendly equipment will cost upwards of $300 ) so power
> savings does not cover the cost.

Okay, let me put it another way.
Let's say you pay 16 cents/kWh for power at home.
Let's just say you know your old 2 GHz AMD Desktop box uses 500 Watts.
And you're going to run that 24/7 because it's a router.
That's 24 h * .5 kW = 12 kWh per day.
12 kWh * $.16 = about $2 / day, or nearly $60 a month.

Which means that the ROI (return-on-investment) of $300 worth of 
equipment that runs at low power would pay for itself in 5 months.   
You can look up specs for the amount of power the CPU, fans, and hard 
disk uses, and that can give you a very rough guess as to the minimum 
power the box might use; this plus looking up what you pay per kWh on 
your power bill and you can re-check what running it as your FW will 
cost you.

Power cost was NOT the reason I went to low-power boxes, by the way.  
Old hard drives, power supplies, and fans are all reliability 
problems.  A low power box with no moving parts that only needs 
passive cooling is a godsend.

> I guess what need answered is how much power does the system take
> while idling. How would I measure that?

A Watt meter.  There's a more complicated way of considering the 
situation if you want to take Power Factor into account, but the good 
news is that you don't need to worry about that because you only 
actually pay for what a Watt meter reads, even though the power 
company has to actually supply you a bit more than that due to Power 
Factor considerations.

   -- Chris

-- 

Chris Knadle
[email protected]

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