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cost of running a pc (in the UK)?

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nudone:
right. i've finally managed to get hold of one of those meter things.

it's a "PM-230 electricity meter" like this http://www.taperecorder.co.uk/energy.htm

i've also calculated the cost of running a few devices. this is what i did if you wish to follow along...

used UKPower Cost Calculator http://www.ukpower.co.uk/running-costs-elec.asp

checked that 10 pence seemed like a reasonable cost for kWh by looking at a pdf file i can't find the link for now - it was for prices starting march 2007 so it looked okay to me.

i used the pm-230 meter gadget to give me the wattage readings for the devices i plugged into it. i didn't bother messing around putting the costs of electric into the device as it was too much for me to read the instructions.

after taking the wattage reading i put that directly into the UKPower cost calculator where it says "(Start from here if Wattage known)" and then i put the hours of use in to the month field. BUT i've ignored the monthly method and just calculated for 24 hours constant use a day, i.e. i put 24 into 'average hours used a month' field and accepted the final result as representing a single day - not a month. (i appreciate you could do a lot of this in your head as the calculations use multiples of 10 but i don't trust my mental arithmetic.)

here are my results:

all costs are for running devices for 24 hours at 10 pence per kWh

main pc setup = £0.54 (i.e. 54 pence to run for 24 hours)
adsl wifi router
24" LCD monitor
amd 4800 dual core cpu, 4 hard drives, geforce 7800, audigy x-fi, 600w psu, several fans
creative 5.1 speakers

without the monitor on at all = £0.40

interestingly, if the monitor and speakers were OFF but remained connected to the mains electric supply they consumed about 4 watts (this wastage gets even worse for other devices as you will see below).


old pc = £0.52
amd athlon 2200, 1 hard drive, non 3d graphics, standard sound card
19" CRT monitor

without monitor on at all = £0.29

and, oh dear, with both pc and monitor OFF but still plugged in at the wall they consumed 46 watts, i.e. £0.11 a day just for doing absolutely nothing at all!!! (the pc used 31 watts when 'OFF' and the monitor 14 watts when off. that's without any LEDs flashing or any indication of the devices being on at all.)


pentium 4 laptop = £0.17
with wifi and 128meg 3d graphics

pentium 2 laptop = £0.06
with wifi card

old apple ibook g4 = £0.08
plugged in but turned off = £0.02



here are a couple of other things

32" widescreen CRT TV = £0.31
on standby = £0.02

14" portable CRT TV = £0.12


i hope that gives you some idea of the price. you can, of course, divide my results by 24 to get the hourly cost.

i think the most interesting thing is the power consumed by devices that are 'OFF'. i know we've been told in the UK to not leave things on standby but i was surprised to see just how bad my old pc and CRT monitor are at wasting energy when they are meant to be off - this is not even standby.

also i think it interesting that my newer pc with 4 hard drives, big 3d card and stuff consumes little more energy than my old amd 2200 machine with hardly anything in it. i know my 600watt psu is meant to be very good at not wasting energy (i.e. heat waste or whatever you want to define it as) but i'm still surprised by the comparison. i guess if i started heavy cpu tasks the power consumption would go up - i should have tested it.

iphigenie:
Well it might mean that when you turn your pc or monitor off something is not really turned off and still using some power...

Were they plugged in directly in the measuring tool or maybe in a fancy surge protecting rail?

I have been looking at http://www.electrisave.co.uk/ - a bit more expensive but you can go around your house and measure what changes when you turn things on/off. Can be found for between £60 and £79 different places around the net. This is making me actually jump and order it

nudone:
exactly, it does mean that the older pc and monitor aren't really off when they appear to be. they are obviously consuming power even though they have been 'turned off' on their front panel on/off switches. during the test they were plugged directly into the meter which then plugged into the mains electric socket. so, it's quite clear that some electrical products simply use power when they have no good reason to. i know some motherboards are set to boot from LAN so they would require power but why on earth does a monitor need to consume electric when it's meant to be completely OFF.

yes, a little trickle of power, i understand that. i tested other devices that were clearly in standby mode and yet they had almost zero power consumption - but this was enough to keep a time display going on their front panel. so there is absolutely no good reason for many products to consume energy in standby mode like the ones i found.

i appreciate that most equipment these days is never really OFF as today's on/off buttons aren't even like the ones we had 20 years ago.

iphigenie, that other device you mentioned for 60-80 quid looks a bit expensive. it's not really going to tell you anything more than the ones that cost around £20. so, you could save yourself nearly 60 quid and then just do the calculations yourself by finding a bit of info online. the wattage is the important thing and you can even get that from the label on the thing you are testing - i just wanted to know for sure what a pc would use as the consumption isn't going to be exactly what the psu states (not that such things really matter when you are talking about days or weeks or months average use).

Ruffnekk:
I heard about devices consuming power while 'off' before, but I never reckoned they would consume so much! Since the device is not really 'using' power, I wonder if it's the result of some sort of leakage.

nudone:
well they are old machines. can't remember exactly but the monitor must be 10 years old. maybe that explains it??? it was a high quality monitor at the time i bought it.

i've just remembered something about the older pc - i think i've got a midi keyboard plugged into it - that could possibly be drawing power. i know it did something weird regarding power but i can't remember what it is now. but that wouldn't excuse the monitor doing what it does.

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