Understanding Computer Power Usage

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waikariboy

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#141094 1-Mar-2014 08:43

So i have a simple atom board doing my downloads (Linux ISO) running 24/7. My understand on this board is CPU 8watt north bridge 35watt. I'm looking at the new 8 core atom cpu boards, cause i wish to have this machine do more. Im trying to learn about how much power i use over the cause of a year. Is there a simple rule i can use to work out the cost of a setup running I.E. Total Power using x current charge of power per hour in nz = $$$. Also should i get a meter to tell me the current usage of power. Any tips would be great.

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#996859 1-Mar-2014 09:15

The meter would probably cost more than the power you use :)

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gzt

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#996870 1-Mar-2014 09:48

For a computer system the wattage rating for each component in your system is a maximum wattage. Realistically unless you are doing some seriously heavy gaming your system will never actually reach that maximum wattage. Power use is measured and billed in watts. You are billed in units of a thousand watts called Kwh. Taking a price of $0.25 per kwh unit your calculation would look like KwhPrice / 1000 * Watts = Cost per hour. Maximum wattage is still a useful figure when comparing components. But for computer systems it is a bit pointless using maximum wattage for actual cost calculations.

How much power a given machine actually uses depends on the tasks it is assigned. As a rule download tasks will use very little power. As a general rule, cpu intensive tasks (like video encoding) will tend to increase power use system wide.

There are sites on low power use computing which rate boards according to the wattage used for various tasks. Mainstream sites like Tom's Hardware also do power tests from time to time to see if manufacturer claims for low power use true. Definitely you can make the right decision at buying time.

I maintain a list of appliance power meters available in NZ. Link below. I'm not sure how well they would compare to lab quality meters but imho they will give an ok relative indication of power use for a particular system over a period of time.

Sideface: The meter would probably cost more than the power you use :)

Agree. Financially you are better off putting time and money into component selection. Every new generation of computing components brings improvements in power consumption.

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Talkiet

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#996875 1-Mar-2014 09:58

Just get one of these... Don't think, just do.

http://www.dicksmith.co.nz/adaptors-power-supplies/mains-power-meter-dsnz-m7319

Putting aside the accuracy (it's reasonable, not perfect), you can switch it around the house for a week at a time on different appliances/groups of appliances. I now, for example, know how much power my 24*7 computers use, how much my TV/Amp etc use per hour when on, how much my fridge/freezer uses...

It also tells you the voltage coming in.

After the earthquakes down here I was without mains power for about 3 weeks but had a 2.2kw generator and I used this to monitor the peak and continuous power usage so I knew I wasn't overdoing it with what I hooked up to the genny.

Cheers - N

Please note all comments are from my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.

gzt

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#996880 1-Mar-2014 10:06

Also available from Countdown, Mitre10 etc as the Elto EMA-1. Jaycar as MS6115. I maintain a set of easy instructions for it here:

http://www.energymonitor.org.nz/elto-ema1-power-meter

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waikariboy

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#996933 1-Mar-2014 11:15

Im trying to work out if spending money on a atom core board from US vs buying something local and what power i would be using over all for a 24/7 server.

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gzt

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#996940 1-Mar-2014 11:35

You will have to do that from a combination of specifications and reviews and some guestimates depending on expected loading. Definitely look at the reviews where they do power consumption tests for various tasks including doing nothing at all. You will get some idea of the relative power consumption for different tasks (even if the models are a bit different) and you can add those together x the time you expect your server to be performing those tasks.

timmmay

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#997037 1-Mar-2014 13:59

Where are you? Someone may have one you can borrow. I do, cheap one, in Wellington northern suburbs.

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raytaylor

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#997900 3-Mar-2014 01:25

The warehouse used to sell those for like $15
I have also seen the mitre 10 ones at Ideal Electrical for $30 or $40

Anyhow I have 4 of them around the house because more of our power bill goes to running computers than the actual household usage so my accountant can claim more than the set rate that the IRD guide advises you to.

Basically a typical desktop computer will set you back $20-$25 a month in my experience if running 24/7
Mine works out to be about $22.50 a month when I last checked.

Useless info: By comparison, an eee 701 with external hard drive netbook uses (at maximum 25 watts) $4.86
Though that only has a 700mhz atom

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