PC energy consumption

Published on: 10th March 2008

Musings on the power consumption of Ginzola's web server PC & energy calculations.

by Daniel Fletcher www.ginzola.com

Ginzola.com has been operational for a number of months now, and I have been developing a number of web sites.  A side effect of this activity has been the need to host test sites that are all based on php/mysql somewhere convenient.  Since I recently moved over to a macbook pro for pretty much everything, my home PC (a rather big Dell Dimension 9200) has become a web server, and is hence switched on 24/7.  This is not a production server understand, just somewhere to to store all my files, and host an array of sites on apache2 simultaneously*.  This has caused me to wonder about it's power consumption...

This PC slightly warms the whole of the upstairs floor of my house.. How much electricity is it using?  Is it worth investing (using a rational energy calculation) to convert the components to greener ones (since speed is no longer of the essence given the file/web hosting role?)

I recently purchased an energy meter, and found that the PC is drawing a staggering 130W on average at the power socket (this is average, it bounces around between 110 and 135W).  You can do this too, then calculate the cost of running it 24/7....

130W x 365 days x 24hours / 1000 = 1,138KW/h

So, with electricity costing around 10p per KW/h, that's £113 per year; roughly £10 per month.

For those interested, here's the spec... (I had to get this off DELL's site with the servicetag feature!)

So what can be done to improve this picture?

Well, it's difficult to separate the dross from the gems on the web, but my feeling is that the processor is mainly to blame in this configuration for a heavy power draw.  There are some excellent resources out there, that express the general opinion that the P4D 945 is a poor performer.    The graphics card was a monster in its day (indeed I fitted a fanless heatsink for noise reasons!)  However the power supply is also a drain on the overall power use.  A break down (and this is only a guess) for the PC running in a normal state (mostly idle)...

Total:130W

At times when the PC is running hard, all these figures jump, but this is not going to be considered here as the question is concerning the overall cost, and the PC spends the vast majority of its time in this state.

By replacing the just processor, the following could be achieved:

So, based on my original cost calculation, the saving of 34W equates to about £3 per month saving!  This is obviously not worth losing sleep over, and writing this article has made be decide that its best to see the life of this computer out as is in this case, or perhaps to keep an eye out for a bargain Intel Core2 Duo processor!; however energy efficiency will definitely form part of my future PC purchasing decisions.

What are the implications on the wider scale?

This has been an interesting exercise to do.  The fact is that PCs use a LOT of power, and that if this is multiplied over a network, then a business needs to consider power consumption in a purchase choice in the face of rising energy costs.  There are examples of pcs out there that are designed with power consumption in mind, the benchmark at time of writing is about 30W total.  Such a network of computers may cost more in the short term, but represents a 75% energy saving over older PC componentry.

*Hosting multiple sites under windows XP is easy with apache2; using vhosts feature.. but impossible with the IIS version that it ships with!  It is possible under windows Vista Business and of course SBS 2003.