Computer Power Usage - Old vs New written 10 years ago

Power Socket

Long term sennir readers will remember I wrote an article a while back on the amount of power my computer used. If you haven’t read it then I suggest you do so now.

Read it? good.

Old vs. New

As you now know, my old computer was ever so slightly out-of-date, and thus has now been upgraded into a modern day beast-a-thon. OK, maybe as much of a beast-a-thon as my pennies could afford, but still, better than the old one:

New Computer

Old Computer

To keep up with this I figured that a big power supply would be needed, and so plumped for one of the 480w varieties (a little modest considering there’s now 1 Kilowatt power supplies available. Yes K-I-L-O-W-A-T-T. Insanity, no?).

So I dugg out the power meter, and here’s where the results get more interesting:

Device “Off” Sleep On
New Computer 10w 12w 130w
Old Computer 11w 12w 152w
Info “Off” means that the computer is switched off, but still plugged in. “Sleep” is using S3 standby. Monitor in standby mode, and speakers switched off. “On” is at the computer’s normal state, with the monitor at average brightness, and with some music playing.

Cost per year

So at idle, I’m saving 22watts with the new computer, and again if we assume 10p per kilowatt, and assuming 6hrs/day usage, rest of time asleep, we get the following numbers:

Device Kwh / year cost
New Computer 364kwh ?36.35
Old Computer 411kwh ?41.17

So bonanza, I’m saving a whole fiver per year! It’ll only take 100 years or so to pay for itself.

Power usage under load

One thing that did occur to me regarding these results is that they record only idle power consumption figures. This isn’t so bad when working out how much it costs, as the average computer is idle for 99% of the time. But out of curiosity I checked how much juice the computer used at 100% CPU load:

idle 100% CPU load
New Computer 130w 184w
Old Computer 152w ???

As I don’t have the old computer in a working state, I couldn’t really test it.

Power Supplies from scan.co.uk
Power Supplies from scan.co.uk

The interesting result here is that with the CPU at full tilt the computer only draws 184w, leaving over 290w available of my 480w power supply. Whilst some of this needs to be reserved for the graphics card (which is limited at 75w from the PCIe bus), that leaves 200w unused. Some overhead is to be expected, but today there seems to be more and more emphasis put on getting bigger and bigger power supplies, when it’s just not needed. The image on the right shows the power supplies selection from scan.co.uk. Here there’s a great deal more > 400w power supplies, when this system needs little more than 350w.

It’s easy to get suckered into believing that modern systems are power hungry beasts, but in reality if you’re buying “normal” components, (and not bleeding edge because you’re not rich), you’re not really too likely to need that 750w+ PSU.

The things on My Desk

Out of morbid curiosity, I decided to check how much juice all the random things I have plugged in at my desk use:

Stand By On
Stuff on My Desk 40w 290w

This made me feel a little better about having them all daisy chained up on multi-way sockets :)

← previous entry | next entry → Sun 20th May 2007 - 21:58 | 16 comments | tagged with Real World, Essays, Computery Stuff

 Comments 16 comments made

Anonymous’s GravatarAnonymous 2 hours later

Your first and third charts contradict each other.

Johan’s GravatarJohan 3 hours later

Cutting down energy wastage is always a good thing. We’re living an unsustainable lifestyle, the dollar cost of energy today hides alot of problems. What about the environmental impact? What is the price of pollution to our health and the hidden costs of cleaning it up? The source of our cheap energy, carbon fuel, is depleting. Due to today’s wastage, what is the cost of energy in 10 years time? What is the cost of gas for our cars in 10 years time?

Spreading the word of “I can afford to waste energy because it’s cheap’ will cost us dearly in the long run.

originally posted by Anonymous

Your first and third charts contradict each other.

Thanks, my copying and pasting fingers had gone loony. The new computer uses 130w, vs. the old using 152w.

originally posted by Johan

Spreading the word of “I can afford to waste energy because it’s cheap’ will cost us dearly in the long run.

I don’t quite get why you think this. The point of the article is that modern computers actually use less energy than older ones, and thus are better for the environment!

If anything the article spreads the word that computers consume a significant portion of the yearly electricity bill.

also Johan(though not the same one)’s Gravataralso Johan(though not the same one) 1 month later

Energy that is consumed today is called “non-durable”, we can only use this energy once. Furthermore, we change our atmosphere when we consume it. Basically, using energy now is turning resources into garbage, it’s turning an opportunity into a problem.

Energy that is consumed today is called “non-durable”, we can only use this energy once. Furthermore, we change our atmosphere when we consume it. Basically, using energy now is turning resources into garbage, it’s turning an opportunity into a problem.

What’s your point, and how does it relate to how much power the average computer uses?

Al.’s GravatarAl. 2 months later

Just a point about your new CPU the Conroe model E6600. It may have the equivalent clock value to your old Athlon but it is generally about twice (!) as powerful and much more efficient (including that 2 cores provides over a single core). As a result temps are cooler in cf. to older CPUs meaning a quieter machine is possible but wrt your article its the efficiency of the Conroe thats makes the difference in power consumption of old and new PCs potentially more impressive that its actually appears “on paper” - you are getting more “bang for the same juice”.

you are getting more “bang for the same juice”.

It’s cool, isn’t it that the same number of watts processes more pixels per second?

The same can’t be said about graphics cards though, which just seem to be using insane amounts of power. This is of course before you start putting two of them in SLI/Crossfire…!

Annonymous’s GravatarAnnonymous 4 months later

hi. please clarify - this looks the wrong way around: Stuff on My Desk: Standby:290w On:40w

Thanks

originally posted by Annonymous

hi. please clarify - this looks the wrong way around: Stuff on My Desk: Standby:290w On:40w

Yes, my word what was I smoking when I wrote this, it should of course be the other way around.

Phil’s GravatarPhil 5 months later

I was wondering if you have considered the amount of energy the computer uses when rebooting after turning it off?

And whether it is therefore more worthwhile leaving the computer on standby??

originally posted by Phil

I was wondering if you have considered the amount of energy the computer uses when rebooting after turning it off?

And whether it is therefore more worthwhile leaving the computer on standby??

I’ve heard this before, and the amount of power used when turning a computer on/off is negligible, so the argument is neither here nor there. Even if we consider a full 300w (very unlikely) usage for 2 minutes turning off/on, that gives us 300w for 4 mins, which is 0.02 kwh.

Now looking above the the figures for standby*, we can see it only uses 2 watts more than when the computer is “off”. So, in theory if we turn our computer on and off again within a 10 hour period we’re wasting electricity, and would have been better off putting the computer to sleep.

So the answer is yes, it might be better to put the computer on standby rather than shut down and boot up again if we know that we’ll be using the computer again soon, but the amount saved is negligible, so isn’t really anything to argue for or against.

*The example here is using S3 standby (sleep mode = very low power usage). Using any other standby mode is a lot less power efficient and if you hear fans whirring, or anything whirring there’s still a significant amount of juice being used in the system, and turning off and on again will be more power efficient.

al.’s Gravataral. 6 months later

Re; standby

Even if it was economical to use standby it couldn’t be used continually since,i believe windows requires proper SHUT DOWN and (re)BOOTING(automatically happens when you switch PC on the next time after SHUT Down anyway) every so often as part of its essential functioning to maintain its “health” longterm. I discovered this when trying to find out why i couldn’t use the fast ‘HIBERNATE’ ALL the time to switch the PC off and on - apparently after so long without ANY complete shut downs and (re)boot you can end up with a nasty mess of registry errors etc.

  • apparently after so long without ANY complete shut downs and (re)boot you can end up with a nasty mess of registry errors etc.

This is all made up.

A non-broken computer can keep windows running perfectly for years. The only reason to reboot should be to install updates/drivers/applications that demand it.

The only reason my ‘puter gets rebooted is if it’s windows update time.

Now shoo, and stop spreading your lies!

Sean’s GravatarSean 4 years later

A non-broken computer can keep windows running perfectly for years. The only reason to reboot should be to install updates/drivers/applications that demand it.

Wow, Rob. You must have the “Never been released” version of Windows that comes complete with other “Never been released” software running on hardware stolen from an alien civilization. I have rarely seen any software or hardware that integrates seemlessly with Windows eg. harddisks that have generate errors, patches/updates which conflict with other hardware etc.

Unless you are attempting some form of sarcasm, I suggest some “self shoo-ing” is in order.

It is a logical phallacy to suggest that “because it doesn’t happen to me, it doesn’t happen”

PS… I have encountered some Linux builds that have performed seemlessly for years.

originally posted by Sean

A non-broken computer can keep windows running perfectly for years.

I have rarely seen any software or hardware that integrates seemlessly with Windows eg. harddisks that have generate errors, patches/updates which conflict with other hardware etc.

I don’t think you read what I wrote? If a hard disk is generating errors, then the computer is broken. If a patch/update conflicts with something, then the computer is broken. This doesn’t fit with my reasoning of a “non-broken computer”. If the hardware you are buying doesn’t work properly with Windows, and it’s meant to work with Windows, then take it back to the shop. It’s broken.

It is a logical phallacy to suggest that “because it doesn’t happen to me, it doesn’t happen”

I don’t think I’ve suggested that. Advice that begins “I believe” or contains the word “apparently” isn’t at all useful. I need some kinda evidence that it’s true - and if I’m staring at something that clearly disproves it then I think I’m at liberty to dispel a myth.

PS… I have encountered some Linux builds that have performed seemlessly for years.

That’s nice. I had a sandwich for lunch.

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