Ultra low power i3 system, 8.5w at idle.

  • I just happened to run across an article about a guy that goes to great lengths to minimize idle power consumption on his desktop systems.  While some (most) of his practices verge on the obsessive, there's still some great info.  He has various systems on his blog ranging from his first 20w @idle Core2Duo system all the way to a 8.5w @idle i3:


    The 8.5w @idle machine was still under 45 watts at full load.  And this wasn't an Atom CPU nor a laptop motherboard, this was an i3 on a desktop motherboard.

    And, in another article, a 5.9w @idle i3:


    Not that people should start breaking out the soldering irons on their builds, here (I can barely solder to a volume pot on my guitar without cooking it), but it certainly shows us what can be done.

  • Thanks for the info…

  • Netgate Administrator

    Inspirational stuff!
    It's a shame his core2duo write up doesn't seem to be available in English. And my Dutch is very bad.  ::)


  • @stephenw10:

    Inspirational stuff!
    It's a shame his core2duo write up doesn't seem to be available in English. And my Dutch is very bad.  ::)


    Ditto, but the Google (chrome) translation seemed decent.  Although a lot of the info seemed to either be fairly device specific or higher level theory and and mindset/paradigm shifting ideas.  That, while good info to have, doesn't lend itself to much of a guide, as I'd wish it to be.  Considering the steps taken, though, most would only be good if you had the exact same hardware, except the theory teaching part, how to identify what needs to be done.  It's hard to write an article that teaches people an "art", or how to envision the inadequacies of a design, as it pertains to that particular goal.  It seems as though some of this may be part of his profession, though, considering the equipment he had on hand and his soldering skills.

    The main thing it told me, though, was that it's quite reasonable to expect a (non exceptional either way; such as no video card, but not a laptop) Core2Duo machine to run about 50 watts at idle, which is what I had been expecting.  And it seems that a good portion of that is eaten up by power supplies that are inefficient at low wattage / idle.  With more efficient power supplies and a just a few of the tricks, there, if we can get C2D machines down to 35 watts at idle, that's almost as good as some dedicated SOHO routers (a lot seem to be rated for 2 to 5 amps at 12v, not that I've broken out a multimeter to test them.)  Since a C2D pfSense box is probably mostly idle unless it's doing some extensive VPN or handling a huge amount of users or bandwidth (or some other CPU intensive… something), they'll probably stay close to that 35 watts most of the time.  Compare that to it's younger brother, the P4 HT, where systems seem to rarely dip below 100 watts (or, so it seems), that could be 60 to 70 watts of savings.  For some people, that's quite a difference and they didn't even have to dip down in to Atoms (keeping headroom for other CPU intensive stuff, if they do so desire.)

    The non-standard stuff he did impressed me, that's for sure.  It was interesting to see how he beefed up some of the power traces on the motherboard and built his own separate ATX +12 power supply because he couldn't find one he trusted.  Oh, and de-soldered the RealTek chip, Because, well... RealTek.

    But, what it certainly did do, it told us what is possible with commodity hardware.  I imagine his sub 10 watt i3 machines would do plenty well as a good pfSense box.  Even if a second Gb nic took a few more watts, I still doubt it'd peak much over 20 watts in all but the most strenuous data handling situations.

  • Netgate Administrator

    Yes I agree that a lot of what he describes is very specific. I was hoping for some insight into enabling power saving features in software. As he says himself he's a hardware guy.
    My own Core2Duo box runs at 30W idle and I've done nothing to it but swap out the CPU and turn on some power saving in the bios (and removed a non-functional VPN card). That box has 7 NICs and an LCD too so it's not especially low powered. Exactly like he says in the blog you need a good reference to know what is possible.
    The thing that my box has going for it is that it's custom hardware and as such can have an appropriately sized power supply, 150W. Still far bigger than necessary but smaller than the 220W PSU in the Lanner 7580 on which it's based. That has to support a wide range of CPUs.

    Probably worth noting that the rating of soho routers is the maximum consumption. My own device I used temporarily (in between IpCop and pfSense  ;)) has a 12V 2A PSU but runs ~12W most of the time. Also that includes the DSL modem and Wifi AP unlike the Watchguard box.

    20W seems like it may be possible with a Pico PSU and properly enabled power saving, perhaps some undervolting. Good target anyway.  :)


  • Yeah, I need to get some good measurement tools.  I only have theories on what my little Celeron 400 Dell box is actually pulling.  Plus all the other stuff I run.

  • This is a great article, and the guy should start a business! I'm sure there could be demand for a monitor/pc that is silent and drinks very little power. I also learned that I overprovisioned my server hardware in terms of power supply (although I had suspected so at the time…) with a 150W picoPSU, perhaps I should have gone for 90W instead...

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