Power Cost Calculations for a PC

[Raistlin]

Quickie, and hopefully not too difficult for someone smarter than me

If I leave my PC upstairs switched on all the time it will obviously use more energy during a 24 hour period than it would if I switched it off every time I'd finished with it.

So, how do I work out how much it will cost to run that computer full-time over a 24-hour period (or indeed any other appliance for that matter)?

Thanks

[xpod]

How about a gadget,something like this mabey?

[Joxer]

What xpod suggests is the easiest option - a computer doesn't use the same amount of power all the time. You could get a rough guess of the maximum by using the rated power of the PSU, so if you have a 500w PSU (nice easy sums) it will use 1/2kwh per hour or 12 kwh a day, find out from your supplier how much they charge per kwh (it may change throughout the day) and multiply it by 12 (on a pro rata basis).

---------- Post added at 20:10 ---------- Previous post was at 20:07 ----------

The heater and heating thread suggest 14p/kWh so that would be £1.68 a day - this is with the monitor off, don't forget to check the power consumption of that too.

[Raistlin]

Thanks for that.

It's going to be running 'headless' once setup (I'll just remote desktop into it), so a monitor etc isn't going to be an issue.

Might try some trial runs with one of those gadgets though - nice find.

At £1.68 per day that's going to add over £45 per month to the electricity bill.....that can't be right surely?

[rogerdraig]

this might help

http://www.ntscomputing.co.uk/conten...computing.html

i would asume it would be less than thier calculations if you are just leaving the base running and less if you can use any power saving features it has for when its not being used

[Joxer]

That was for a 500w pc running absolutely flat out - it won't be and probably won't be anywhere near 500w - link supplied by rogermevans suggests 135w - that would be with a monitor, judging by the rated power on the back of my pc and (15" CRT) monitor it will be less than half that so keeping the sums easy it will be between 50 and 100 watts or between £4.50 and £9.00 a month.

Then again that page is for 2007 so power consumption might be a bit low.

You do realise I am pulling figures out of a hat mostly, even if I am citing sources.

[rogerdraig]

yep though with those figures and he power rating on the pc he has it should be posible to get a good guess

[kpanchev]

General effectiveness of PC power supplies is 70-75%, so if it is let's say 700W max output power, it will use roughly 0.94 kW input. Again, this is IF you manage to utilize it to the max, which is very unusual. Normally it'll be at half power max, and most of the time in power saving mode. Expectations for running a headless pc non-stop (server or proxy probably) are around 0.5 to a pound a day max.

(Calculations are very rough and based on electricity prices taken out of thin air, as I can't remember them exactly)

[Kymmy]

Firstly although you have a 500W PSU it doesn;t mean to say that the power drain is 500W..

Use this to work out your power drain.

The work out the rest using the already quoted 70% effeciency to get the mains side figure, then work out daily/monthly/yearly energy figures...then check your electricity bill for costs of the electricity..

[AbyssUnderground]

Buy a power meter from maplins for £10 and use it to find out. You can use it for other things around the house too. You'll be horrified how much some things use in standby You'll also be quite surprised over how little your PC uses compared to what you think it uses.

(Also, computer power supplies are often up to 95% efficient, but only at close to the rated load, in case anyone thinks otherwise when looking at the label on their PSU.)

Once you have the figure, go to http://www.abyssunderground.co.uk/ca...nningcosts.php

Enter the watts, pence per kWh, hours, and hit submit.

EG for me, its 120 watts @ 14p/kWh for 24h/day:

£0.46 per 24 hours
£3.23 per week for 24 hours a day
£12.9 per month (28 days) for 24 hours a day
£38.71 per quarter (3 months) for 24 hours a day
£167.73 per year for 24 hours a day

Also if you're running it headless, you won't need a powerful graphics card. Use the on-board if you have any. Sound isn't needed so remove sound cards if it has one. Also tell the HD's to turn off after 10-15 mins of inactivity to further reduce usage when its not in use.

I specifically designed my server to be very power efficient, unfortunately the hard drives made it somewhat infficient... 64watts inc 1 HD, shoots up to 120watts with 4 + 2 external. The externals turned off reduces it to 104watts, so the 1tb drives I have are quite hungry. Still, mine turn off overnight (I think) so it should reduce it. I need some logging equipment!

</babbling>

[Gary L]

I used one of those plugin meter things and it works out to around £3.50 a week to run 24hrs a day.