How Much Does Your PC Cost To Run?

Written by Paul Goodhead

November 6, 2011 | 11:09

Tags: #intel-atom #media-pc #power-consumption

I’ve recently put together a media PC for playing music in my kitchen. It’s just a simple little Intel Atom-based box, but it does all I need for the 40 minutes or so I usually spend cooking or washing up. Its one negative issue is that it takes a little while to boot up and get into Windows Media Centre - a fact that has put my housemate Jack off using it as he doesn’t tend to spend as long in the kitchen as me. By the time it’s booted up and ready to go, he’s nearly ready to turn it off again.[break]

This led to him suggesting that we simply left it in Sleep mode, rather than turning off the PC when we were done with it, meaning it would boot up in a fraction of the time. This was something I was initially dubious about; most of my childhood was spent being told by my parents that leaving things on standby cost money. Are you using it? No? Well turn it off then. That was how the conversation usually went.

Fortunately, a lot of advice that parents give kids isn't true (my eyes still aren’t square from sitting to close to the TV), so I thought it was worth looking into just how much power the PC would consume if we left it on standby between uses. To this end I borrowed a power monitor from the labs and set off home to see just how much juice my little media PC drank.

How Much Does Your PC Cost To Run? *How much does your PC cost to run?

Plugging in the monitor and powering up the system showed the entire PC (that’s the box, screen and speakers) to consume around 50W when active and only 5W when in standby. The screen was also found to be a major energy draw; turning it off while the PC was playing music dropped the power consumption down to 29W.

What does this actually mean, though? Is this a lot? How much would it cost to keep the PC in standby? Is this media PC going to bankrupt me? To find out, I had to look up how much we were paying for electricity and convert my Wattage readings into the Kilowatt hour units that form the basis of charging for energy in the UK.

Doing this required some simple maths, which essentially runs like this:

How Much Does Your PC Cost To Run? *How much does your PC cost to run?

Assuming a worst case scenario of the PC being left in standby for every hour of every day in a month, and using the standard dual fuel, quarterly billing electricity tariff for central London from Southern Electric - the equation then becomes this:

How Much Does Your PC Cost To Run? *How much does your PC cost to run?

Following the equation through to its natural conclusion gave us a frankly laughable figure of 41p. That's 41p to keep my media PC in sleep mode for an entire month. You can’t even buy a chocolate bar for 41p these days. It wasn't quite the huge power drain that I’d imagined then, and the cost was well within our household budget.

With the media PC examined we naturally started wondering what other electrical items cost to run. We were amazed to find that the kettle consumed 2,250W when turned on - a prodigious amount compared to the media PC. Given that it’s only in use for a short while though, its energy cost is relatively minor. Allowing for the kettle to be boiled 41 times a week (5 per weekday, 16 times over the weekend) and allowing 1 minute per boil still works out as a measly cost of 74p per month.

More interesting possibly was my main gaming rig. This consumed 355W when both its CPU and GPU were under maximum load (again, this is a worst case scenario; few games are likely to do this). Allowing for 20 hours of gaming a week (two hours a night in the week, and five hours a day at the weekend) this equates to £3.43 a month, or roughly £10.29 per quarterly bill or £41.16 a year.

In truth, I was surprised by how little energy everything consumed, especially given the size of our normal bill. There are, of course electric devices in the house, such as the immersion heater and oven, which we simply can’t gauge with our equipment, no matter how interesting it would be to do so. Have any of you done anything similar at your own home? Have you identified the single biggest power drain in your house? Let us know your thoughts in the comments thread below.
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