Building A Very Low Power, Full Featured Desktop

For a few years now, [mux] has been playing around with extremely efficient computation. In 2010, he built a fully featured MiniITX / Core 2 duo computer that only consumed 20 watts. Last year, [mux] managed to build an Intel i3-powered desktop that was able to sip a mere 8.3 watts at idle. He’s back at it again, and now his sights are set on a fully featured Intel i5-powered build with a built-in monitor that will draw less than 6 watts of power.

Like his previous 8 watt i3 build, [mux] reduces the power requirement of his build by carefully measuring the power draw of every component on his board. The power savings come from a simple fact of any power supply; when converting from AC to DC, or from one DC voltage to another, there’s always a little bit of power lost in the process.

[mux] reduces these power losses by removing a few voltage regulators and re-routing power lines across his motherboard. So far, the power draw on [mux]’s computer is more than half of what it was when the parts were stock, and we can’t wait for the finished build that includes a built-in monitor, UPS, and a proper case.

48 thoughts on “Building A Very Low Power, Full Featured Desktop

  1. In other words, a PC could be far more efficient if there were several power connections from the supply to the motherboard, to avoid long and inefficient power lines in the PCB.

    It’d just look even more like a rat’s nest. ;)

    1. If you mean it draws 500W while running a game, nothing of what he talks about here is going to shave more than ~10W off of that. Unless you can find a way to reduce power consumption of the silicon in your CPU and GPU (and trust me, Intel/ATI/NVidia have tried…) you’re not going to make much of a dent in anything but the relative power consumption of an *idle* machine.

      1. Well, technically my mods do very much impact system power consumption under load as well… Improving power delivery chain efficiency, optimizing power planes and reducing chip temperature under load together can easily make a 25% improvement.

  2. raid not useful?!? i guess if your goal is to reduce power and if you don’t value your time, then yes, it’s not very useful. i’d much rather take 10 minutes to replace a hard drive (and that includes having to take time to order the replacement) than i would to spend 3 hours to rebuild the machine.

    besides that, if the goal is power savings, then why not limit the build to just one ssd? spinning platters are very inefficient.

    i don’t think i would go this far just to save a few watts. engineers smarter than i am designed the board and i’m sure they had their reasons for the choices they made.

    1. “raid not useful?!?”

      I believe he was referring more-so to raid0 for performance. Although that said raid as a backup solution for a homePC really is a little silly to me. For most (yes I’m using a generalisation) an external backup taken once every day or two is sufficient.

      “besides that, if the goal is power savings, then why not limit the build to just one ssd? spinning platters are very inefficient.”

      Just because he’s saving power doesn’t mean he doesn’t need some storage.

      “engineers smarter than i am designed the board and i’m sure they had their reasons for the choices they made”

      Yes. It’s called designing to a cost. It’s not such a bad thing… it saves you a couple hundred bucks on upfront costs, but it certainly doesn’t lead to the optimal solution in most cases.

      1. I’ve read otherwise. :)

        Depending on the model and the SSD, there can be a huge savings in battery usage. LowEndMac has a lot of info on adding SSD drives or CompactFlash cards to the older laptops for weight and battery savings. Some users doubled their unplugged use time.

    2. RAID-0 and RAID-1 are what I was aiming at, and yes, they are very, very inefficient ways to reduce your downtime. Especially with RAID-1 what you’re doing is doubling system complexity (and thus failure rate), doubling system cost, doubling the impact of any non-harddisk related failure (e.g. power supply failure, which is often just as likely as hdd failure) and what do you get? You reduce the downtime of your machine when one of the disks fails. (e.g. you don’t have to restore a backup, which can take a couple of hours with a multi-terabyte disk).

      RAID-0 is entirely useless nowadays, we have SSDs to boost performance in a much more profound and cost-effective way.

      1. I believe you’ve already received enough comments about your ideas about RAID 0. Applications like video rendering and data manipulation could most definitely stand the speed boost offered by RAID 0. I recommend checking out Wikipedia or googling for some RAID 0 benchmarks on SSD’s before claiming it’s not worth it.

  3. Nowadays, I run a laptop in place of my desktop pc. The desktop was just too big, loud, and power hungry. The laptop idles around 10-12w – I put in a SSD, so this probably also contributes to power savings. My laptop also puts out less heat, so my room doesn’t get nearly as hot as before.

  4. It seems to me that if this were a good idea, then the manufacturer would have done it in the first place. If it works then it works though. My laptop draws 8 or 9 watts off the battery with the screen dimmed way down, and laptops are designed specifically to use low power. So this guy’s 6 watt figure is impressive.

    1. Usually the engineers aren’t that good, or they have limited time to optimize the product before they shove it out of the door. Simple manufacturability concenrns may weigh more than efficiency, so it becomes more cost-effective to slap in two regulators instead of routing power all the way across the board.

    2. Don’t forget that like my computers, laptops are usually designed with very tight power envelopes in mind. Less design space means you can optimize much easier. That, and desktops don’t actually have to run off batteries.

      That being said, my 5-year old core 2 laptop uses like 25W idle. It’s ridiculous. No care at all has been given to power consumption.

    3. Engineers designing desktop PCs optimize for cost, performance, ease of manufacturing, time to market and sometimes reliability.

      There is little incentive to optimize for power consumption, it’s simply not demanded by the market, yet.

      Laptops and cell phones have more effort put into power inefficiency but other design considerations will often take precedence.

      The statement: “…if this were a good idea, then the manufacturer would have done it in the first place” is almost never true.

      If it were true then products would never improve because they would have been built optimally the very first time.

  5. Very interesting read. The design of the enclosure is very cool, basically using it as a giant heat sink.

    @Dan Power efficiency isn’t really a top concern for desktop computers. I am paying around .10/kwh right now, so a 100 watt desktop is only going to cost a few bucks a month, assuming it’s used all day.

    1. spot on man :)

      … that, AND the fact that if all desktops were just as efficient as laptops, they wouldnt sell as many laptops :P
      ( to people trying to stay cool in the summer)

    1. For fun, because it’s difficult, and because they can. Not because it’s terribly practical.

      It’s the same reason people try to make faster computers, run marathons in shorter time, or build taller buildings. Or any of a million other things.

    2. Well…. the 2010 census shows a little over 76% (or around 91,724k households have some type of computer)

      1 watt here or 2 watts there doesn’t seem like a whole lot but when you start multiplying that across the entire computing population, those numbers do start to add up.

    3. For science!

      No seriously, for science. Power electronics in consumer stuff is actually really, REALLY cutting-edge nowadays. You can usually find stuff on motherboards that isn’t even available for people like me (i’m a power electronics design engineer by the way). So tinkering with that stuff and trying to power optimize it (instead of cost optimizing) is a nice practical exercise of all that theory I got at uni.

    4. People who run a lot of computers do this sort of thing because it saves a lot of money.

      Consider Google or Microsoft – they run a LOT of machines in their data centers. So even a small savings multiplied by a huge number results in
      a big savings (both in powering machines and in
      cooling). Thus Google, e.g. designs their own servers to among other things reduce energy use.

    5. When my wife moved in with me years ago, I had to setup a little office workstation for her. I stuck it in a corner of my living room and for years I had to run a really long extension cord around the perimeter of the room to draw power from the single outlet in that room. I live in an apartment in Queens, NY and have southern-facing windows that let in a LOT of light. I hung Harbor freight folding solar panels in the tops of the windows, so you could still open them, and hid them with shades. I took a 40-pound kitty litter bucket and populated it with a bunch of leftover UPS batteries, a charge controller and an inverter (even though it’s not usually used). Now my wife’s computer is literally wireless. Her laptop and desk lamp run off the 12v power station! This article means a lot to a guy like me. Thanks!

  6. I remember this guy, last time he removed galvanic isolation between mains and output to save 0.1W of idle power or something.

    >some additional mods that I’m not going to tell
    >(because they’re dangerous)

    haha he learns, this time he didnt even bother to tell us how dangerous his creation is :)

    1. Heh, that’s really all you remembered from that ;)

      This time the power supply is galvanically isolated from mains. I had a fair bit more power supplies to tinker with this time so I didn’t have to resort to drastic measures.

      1. Have you considered using an Ipad charger?

        Genuine Apple chargers have some of the highest ac->dc efficiency i’ve ever seen. And it shows if you take it apart and look at the board design inside them.

    1. Then you’ve got a very low-end, slow, expensive and hard to customize machine. That’s no challenge, everybody can throw money at a problem. The interesting bit here is to make a very high-end system use less power than a low-end laptop.

      1. I keep telling people it is better to use your brain than your wallet, but nobody listens, except Business people every four months.

        No wonder why everyone is in debt!

        Besides, most problems are smart cow problems. It only takes one smart cow to open the gate and the rest can walk through. Kudos on being the smart cow.

      2. Hi,

        nice to find and read your blog (partly via Google Translator only).
        Could you be a bit more specific about the mods.
        I would do some slightly modifcation too. I.e remove unwanted LM317 (for TPM) or similar hacks like rerouting powerlines as you did using the fat yellow wires.


  7. do you want more saving ? use the color eink as display.
    if we use eink for the display it will save more power.

    i think color eink can be used as office monitor, which can save a lot of energy and also make our eyes better, because more easy to the eyes/ not make our eyes fatique

  8. “So far, the power draw on [mux]‘s computer is more than half of what it was when the parts were stock, and we can’t wait for the finished build that includes a built-in monitor, UPS, and a proper case.”

    I did nothing to my computer and was also able to make the power draw more than half of what it was.

    (Do you mean *less* than half?)

  9. MUX.
    I am working on a LENR system that should put out somewhere around 10 to 15 W of power at 12V DC (using conversion of heat via Peltier chips). I would like to use it to power a laptop for a standalone demo/presentation. Are any of your low power systems available? Do you have any advice on which lap top might use the lowest power (without battery charging)?

  10. If it is all about power conservation, which is a good thing because in the US we could cut the energy consumption to half by proper energy conservation, then change your habits:
    1) Switch off your computer when you leave your desk, or at least reduce the time for it to hibernate
    2) Stay away from fancy animated screensavers, they use a lot of CPU power. They are an icon from the time when we used CRTs and are useless for LCD displays. An insurance company changed in their office building screensavers from animated to static and they saved several KWhrs/month for their 900 workstations.
    3) Changing the AC setting in summer 2 degrees higher, and in winter 2 degree lower, this will save you enough energy to run 10 PCs.

  11. Some of the cynical responses here fail to appreciate sometimes computers are not plugged into a limitless power source.

    I personally am researching use of ICT on a remote Scottish island, where the off grid supply comes from solar power. Indeed countless other areas exist – mobile computing (hill walking, rescue, disaster help), difficulty environments (underwater, sealed areas such as isolation units, even space…), economically challenging (too poor to afford, too expensive to generate), etc

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