October 24, 2005
Between my server and my Windows Media Center home theater PC, I have at least two PCs on all the time at home. Have you ever wondered how much it's costing you to leave a computer on 24 hours a day, 7 days a week?
The first thing you need to know is how much power your computer draws. The best way is to measure the actual power consumption. You'll need a $30 device like the Kill-a-Watt to do this accurately. Once you get one, you'll inevitably go through a phase where you run around your home, measuring the power draw of everything you can plug into a wall socket. For example, I learned this weekend that our 42" plasma television draws between 90 watts (totally black screen) and 270 watts (totally white screen). Based on a little ad-hoc channel surfing with an eye on the Kill-a-Watt's LCD display, the average appears to be around 150 watts for a typical television show or movie.
But I digress. Once you've measured the power draw in watts (or guesstimated the power draw), you'll need to convert that to kilowatt-hours. Here's the kilowatt-hour calculation for my server, which draws ~160 watts:
160 watts * (8,760 hours per year) / 1000 = 1401.6 kilowatt-hours
The other thing you'll need to know is how much you're paying for power in your area. Power here in California is rather expensive and calculated using a byzantine rate structure. According to this recent Mercury News article, the household average for our area is 14.28 cents per kilowatt-hour.
1401.6 kilowatt-hours * 14.28 cents / 100 = $200.15
So leaving my server on is costing me $200 / year, or $16.68 per month. My home theater PC is a bit more frugal at 65 watts. Using the same formulas, that costs me $81 / year or $6.75 per month.
So, how can you reduce the power draw of the PCs you leave on 24/7?
- Configure the hard drives to sleep on inactivity. You can do this via Control Panel, Power, and it's particularly helpful if you have multiple drives in a machine. My server has four hard drives, and they're typically asleep at any given time. That saves a solid 4-5 watts per drive.
- Upgrade to a more efficient power supply. A certain percentage of the input power to your PC is lost as waste during the conversion from wall power to something the PC can use. At typical power loads (~90w), the average power supply efficiency is a disappointing 65%. But the good news is that there's been a lot of recent vendor activity around more efficient power supplies. The Fortron Zen fanless power supply, for example, offers an astonishing 83% efficiency at 90w load! If you upgraded your power supply, you could theoretically drop from 122w @ 65% efficiency to 105w @ 83% efficiency. That's only a savings of $20 per year in this 90w case, but the larger the power usage, the bigger the percentage savings.
- Don't use a high-end video card. I'm not sure this is widely understood now, but after the CPU, the video card is by far the biggest power consumer in a typical PC. It's not uncommon for the typical "mid-range" video card to suck down 20+ watts at idle -- and far more under actual use or gameplay! The worrying number, though, is the idle one. Pay close attention to the video card you use in an "always-on" machine.
- Configure the monitor to sleep on inactivity. This one's kind of a no-brainer, but worth mentioning. A CRT eats about 80 watts, and a LCD of equivalent size less than half that.
- Disconnect peripherals you don't use. Have a server with a CD-ROM you rarely use? Disconnect the power to it. A sound card you don't use? Pull it out. Redundant fans? Disconnect them. That's only a savings of a few watts, but it all adds up.
If you're building a new PC, it's also smart to avoid Intel's Pentium 4 series, as they use substantially more power than their AMD equivalents. Intel's Pentium-M, on the other hand, delivers the best bang for the watt on the market. Although it was originally designed for laptops, it can be retrofitted into desktops.
Posted by Jeff Atwood
It is interesting reading the comment list here - there is such a disparity between those who "get" the whole greenhouse gas emission problem, and those who just don't "get" it (or who turn their minds off whenever it is mentioned).
We were discussing in the office whether some of the opinions and stories presented in a forum like this, reflected the statistics presented in data like this:
It's fun to play with the numbers a bit. For example, if we assume an average of about 1kg carbon dioxide emission per 1kWh, that means that Jeff's server's emissions alone are higher than the lowest 78 countries' per capita emissions!
Kind of explains why other countries get a bit narky with America sometimes.
Thanks alot for the insight.
My electricity bill is the lowest of all my bills. Cable/Internet bill is higher, Phone is higher, Gasoline is higher, Heat is higher, even in the summer with AC its pretty low ($80-120/mo)
very interesting facts about power consumption.
Just a question how much affect the age of the hardware in the power consumption I mean the difference between a P3 and a Core 2.
Let me put myself as an example I have an iMac 20 (Intel Core 2 Duo 2.2GHZ) which I use as a server for music and video for an XBMC, download torrents and process stuff (rendering models for engineering) while not in use, and obviously I use it for work during the day so it's on 24/7; this is my actual situation but I get an old toshiba laptop with a busted battery (1.2 ghz Celeron) so the question is what happen if i swap the laptop during the nights for post processing of my work of the day and shut the imac since both will work with the screen off, wifi on, and both have very similar power supply and architecture and the laptop will work more time because of the slower processor; so its possible that a recent desktop waste less energy than an old laptop???
I have to say that the laptop is considerably more noisier than the laptop
I hope someone read this and put your opinions about this, I'll try to get a current meter for the weekend and make some actual testing but in the meantime what do you think???
Forget the refrigerator, the microwave oven, the dryer and the washing machine there is a new king in the throne: the almighty Apple iMac. I've got that current meter and do some testing in my home.
Here are the results. First In one circuit I've got the Internet modem which is a Nexnet wireless and is hooked up to my router which is an Airport Express (I choose it because I figure something so small can consume so much energy!!! ) I was wrong together the two of them get 24W and the iMac with the screen off, WIfi and Bluetooth On and doing some minor processes get a result of 29 W and the old toshiba laptop also with the screen off wifi on and doing the same process get a reading of 21 W so my question get answered. Desktops waste more energy than laptops no matter how old they are but even worse the tiniest router in the market consumes almost the same energy than a computer just idling as a home server, well maybe my Internet modem wastes most of the 24 W I'm going to check it out in the future.
I didn't tell you why the iMac is the new king.
IF i get the power of the iMac the airport Express and the modem y got a total of 53 W and they are ON 24/7 so it cost me $ 83 a year with a cost of 0.18 $/kWh wich i admit maybe is not that much but in other way it consumes 40 kWh/Month of the total 200 kWh/month so the 20 % of all electricity just goes to the computer, and its just the beginning because I'm not counting the other two computers the media center and the other two airports which are on and Off during the day and the time when I am actually using the iMac, which is a lot, so i think 40% to 60% of my electrical bill just goes to the computers.
but im not going to use the laptop because the difference is just about 15 $/year and its too much hassle using two computers.
well I found that the internet modem consumes 18 W all the time so the airport express only takes 6 W.
I just wanted to say I have come across this post several times when researching energyconsumption of computers and I keep loving it with every visit!
I have an old gaming PC that I leave on all the time to stream media to an Apple TV, and I keep wondering how much of a difference it would make if I downgraded to the world's most energy efficient desktop, the Mac Mini.
My server runs a Via C7 mini-ITX formfactor (1.2GHz c7 cpu). It fits behind my desk, and when using a picoPSU and a 60W 12V brick powersupply, a kill-a-watt measures it at only 18W! I put it together with a 100GB laptop hard drive for about $400, and since I have become addicted to having a server up 24/7 this machine will pay for itself in a little over 2 years, as well as using about 10% of the power my p4 rig was using.
These are some great tips even in today's world of computers. Businesses are becoming more and more cost oriented, so finding ways to save them a few dollars is really beneficial for them.
How To Make Your Computer Faster
There is also lots more you can do such as disabling uneeded hardware built into the computer, this includes modems and cards, and even CD/DVD drives, making sure you have the lastest firmware installed.
I have a pc which needs to be left on between 8am - 1am 5 days per week, i set it in the BIOS to power off and on between these hours, i used this to disable everything possible, its written for a laptop but most of it still applies.
Computer Power Saving
I currently use two of those suggestions on my home setups, the monitor sleeping and unplugging unused peripherals! You would be amazed how much electricity a usb cable can use up through phantom charge in a day, nevermind a year!
We run a computer repair service in Jacksonville, Fl. To find out more visit http://www.duvalcomputingservices.com
In the current climate everybody would like to save money which is why many people switch to energy efficient solutions which are cost-efficient. Low voltage track lighting is just one way to save money as it certainly saves on the electricity bills and it is becoming more and more popular for this reason as well as being an outstanding, state-of-the-art solution for task and accent lighting.
It is about us helping the environment and saving energy. CPU take a ton of energy to run all the time. The cost of all of doing it must be something fierce. I wrote about this kind of spending at my ( www.thecashteacher.com ) and hoped people would save where they can. This is definitely one area of interest.
Appreciate the tips posted here. Keep up the nice work. Saving on consumption of power is the utmost priority. Considering the huge number of systems working globally even a minute saving from each person will transform to a big benefit for mankind.
Wish to apply the suggestions in my work places. Convinced that a bit of contribution from every one will keep away the environmental disasters.
Actually, the other day I've heard an interesting argument in favor of iPad against regular laptops. Apparently it takes only a few seconds for an iPad to start up compared to a few minutes for a laptop after it's been turned off, which can be annoying. So maybe the answer to energy saving is switching to iPads?.. (No, I'm not paid by Steve Jobs!)
Many computer users don't like to turn off their computers because they believe it will bring them hardware problems or they just don't want to close their open programs or simply they don't want to wait for the startup process. In the views of computer tech news leaving the computer on when you finish your work might not help to prevent any hardware or software problems, and it is also wasting energy and money.
The technology is relatively new, yet proven. However, most organizations have not realized the tremendous opportunity for harvesting energy savings in IT systems, like various types of cancer and knowledge on all of them is necessary for defining what treatment you need. Those that evaluate the opportunity normally wonder why they do not already have power management.
Wow! I had no idea until recently leaving these devices on could be such an energy drain. I recently found out that leaving your printer on eats up a huge amount of wattage, so I started turning it off. Now I will turn my laptops off as well. I wonder if anything can be done to reduce big screen tv usage.
I live in São Carlos, Brazil, and here the kilowatt-hour price is around 7 cents an hour (and that is in reais!, something close to 4.5 dollar cents.
Leaving PC on can "kill many watts" as suggested in the post. Wouldn't it be just better if we simply switch from grid electricity to alternative solar power. Here is an article that I found http://gomakesolarpanels.com/advantages-of-solar-power/ while searching for renewable energy sources and in spite of the costs I am contemplating making a switch ASAP!