Building an Energy Efficient, Always-On PC?

An anonymous reader asks: "Like many readers, I find it necessary to leave my home PC running 24/7, for things like web or FTP servers, BitTorrent, or simply to make sure I don't miss any messages on IRC or my instant messaging client. It has been about 3 years since I built my current PC, and keeping it running all the time uses a lot of juice. With my next PC, I would like to do what I can to keep the power-consumption to a minimum, without sacrificing processing power or other features. What should I look for when choosing components for my PC, and what other ways are there to keep the power consumption down?"

Dont bother.

[brejc8]

Energy efficient in which way? For the sake of the planet or for your electricity bill?
Generally the energy expended into making a product is directly relative to its price (see Marx and Aristotle). Whether the product is fantastically overpriced and the profits are used to fly CEOs around the world in personal jets, or if the product is made in a sweatshop where the workers are obviously not earning that much and have a greatly smaller carbon footprint than others. Every cent you spend is in turn spent on

Re:

[Eivind]

What you say is more or less true. But cost-of-purchase ain't the only part counting. Total cost is what counts.

So, a more expensive solution that uses less power, and thus ends up costing less in total, over the lifetime of the PC, will likely also be more environmentally friendly. It'd be better for your electricity-bill too.

At $0.15/kwh, saving 50W (say going from 100W average to 50W average) is worth $65/year in a always-on device. So, if such an always-on home-server is used for 3-4 years, that sav

Re:

[daeg]

It also depends on how the power is used. If it's being used in the CPU, it's going to kick out a lot of heat, which can't be ignored, either, although can be hard to quantify. If your system is using less power, it's also probably kicking off less heat. If you're in Florida like me, you should pay attention to that, considering most Floridians air condition for 10-11 months out of the year.

Re:

[swillden]

It also depends on how the power is used. If it's being used in the CPU, it's going to kick out a lot of heat

Actually it doesn't matter where it's being used, in the CPU or elsewhere, every watt into your computer is going to end up heating your house.

If your system is using less power, it's also probably kicking off less heat. If you're in Florida like me, you should pay attention to that, considering most Floridians air condition for 10-11 months out of the year.

OTOH, if you live where you have to heat your house a large part of the year, the heat it gives off may offset the energy cost. In my case it's a little more expensive to heat with electricity than with natural gas so the energy into the computer isn't free, but the heat does effectively reduce the cost a little.

Re:

[pthisis]

Actually it doesn't matter where it's being used, in the CPU or elsewhere, every watt into your computer is going to end up heating your house.

Not _every_ watt. Most watts. Things like light and sound going out the window don't heat the house; they're pretty negligible power-wise, but I wouldn't be too surprised if a few watts from a wireless card heat the outside world rather than your house.

Re:

[Eivind]

Actually, no. It does not matter where the power is being used. All of it turns into heat regardless.

Re:

[Shakrai]

Actually, no. It does not matter where the power is being used. All of it turns into heat regardless.

Yes, but not all of that heat is helpful to me. The photons leaving my monitor that escape through the glass of my window and go into my neighbors house aren't doing very much for me ;)

Re:

[bcrowell]

Well, the OP didn't say whether he was interested in low power in order to save on his electric bill, or for ecological reasons, or both. But you're right, it's not necessarily ecologically sensible to buy new hardware. In my area, the garbage company runs a disposal site for hazardous household waste, and when you go there, you see big stacks of computers. They have a program where if you ask, you can take computer hardware for free. For someone who really wants to do a favor to Mother Earth, it might be a

Re:

[smchris]

Seems relevant. He doesn't say whether he has a T1 to the home but, if not, it seems like his modest needs probably don't require anything like a three-year turnover. Our home DSL web server does what we need with an 800 mhz Slot A and a 2-gig scsi (recycled from ebay at 4+controller for $30).

Third World way to be efficient. Don't toss it if it works.

Re:Dont bother.

[smallfries]

I'd agree with your points about the cost of making a new machine versus the savings; but instead of saying don't bother I'd recommend playing with the software a little. Lots of people have "24/7" servers at home for the same applications, but how many people actually use them 24/7? With me it is more a case that I want access 24/7 even if I just use it a few hours a day on average. Have a look at a hibernation kernel and WakeOnLAN. If you can bring the server up to a good point remotely with just 30sec latency then the real power saving is having it shutdown 80% of the time. Using a longhaul governer and scripts you can ensure that it stays up when it needs to (ie during a bittorrent download) but then shuts down when there are no active processes on the system.

Re:

[smallfries]

Well I haven't made it work yet :) But I have a very weird bug in the nvidia driver that only seems to affect my configuration out of the whole world. Basically if you can't switch SBA off in the driver then hibernation won't work. If you (like the rest of the world) can then hibernation is very easy to setup and works likes a charm. I haven't played with the WakeOnLAN part as currently it would be a little pointless for me.

Re:

[try_anything]

Right! That's why I get paid more than my former classmates. I eat and consume much more than they do.

Re:

[syphax]

Every cent you spend is in turn spent on power

Would someone please explain this logic to me? I mean, I understand the logic (If I pay Sally for a hummer, she might use the money to pay off her Hummer), but I just don't think it is valid. Sure, if you plot energy use vs GNP on a log-log chart (like at GapMinder [google.com], there's a relationship between CO2 emissions (a proxy for energy use, indexed for relative environmental impact) per capita and income per capita, but there's a lot of scatter and a lot of trends th

Re:

[brejc8]

First of all, thanks for pointing me to that gapminder thing. Hours of fun.

The simplified model is still true for the price of a product. The thing that the GDP vs energy use model doesn't show is the money movement. There has always been a massive movement of money to China where they have a huge manufacturing base. Effectively when you buy that made in china toy you're sending a packet of money to china for them to spend on burning power.
The model does break down though in service industry based economies

Not one... two.

[Baddas]

Use two PCs. One small Via Epia 700mhz to do your webserver and bit torrent, and another PC with whatever spec you desire to use when you need to do processor-intensive stuff.

If they're networked, you can just as easily copy files over when you need them, or stream media across.

Re:Not one... two.

[PipOC]

A C7 would likely be a much better choice for a webserver, you get SATA, and a much faster processor, which is much more suited to serving web traffic. And if you're hosting torrent files you will likely be having lots of disk access, making SATA a huge benefit.

Re:

[jgrahn]

A C7 would likely be a much better choice for a webserver, you get SATA, and a much faster processor, which is much more suited to serving web traffic.

Since when do you need a fast processor to serve web pages over a (most likely) fairly slow link?

And if you're hosting torrent files you will likely be having lots of disk access, making SATA a huge benefit.

Only if IDE disks cannot fill his internet connection. I seriously doubt that is the case. And how fast disks do you need to fill IDE, anyway?

Re:

[AusIV]

I'd also think you could use wake-on-lan to get the lightweight to wake the heavyweight either at predetermined times, or on certain events that would require the heavyweight.

Re:

[SanityInAnarchy]

I've done exactly this, although I wasn't going for anything particularly lightweight -- it's a 1.8 ghz amd64 with a gig of RAM. But, for instance, I can SSH in to the server and have it wake the desktop, then SSH into the desktop and tell it to reboot to Windows, then VPN+rdesktop, if I need (for instance) a real version of MS Office on the go.

One thing I'm toying with is finding some sort of device which can be controlled via USB or somesuch to turn on and off power at will. Thus, I could have the server

Re:

[bobbozzo]

A Taiwanese company called GemBird makes USB controlled power strips.
Some info and a pic at:
http://people.debian.org/~ocsi/project/sispm [debian.org]

They were at CES last year trying to find a N.A. distributor. It doesn't look like they succeeded:
http://www.gembird.cn/index.html [gembird.cn]

I wouldn't say their stuff is particularly high quality, btw.

Re: remote power control

[tchuladdiass]

Baytech makes serial and ethernet controlled RPC modules. A cheaper approach for home use would be X10 power modules (if you don't want to buy the ones from X10 corporation, there are a a couple of third-party ones that Home Depot sells).

Re:

[Znork]

"One small Via Epia 700mhz"

To skimp even more, one could take a look at linux based/capable NAS and/or DSL router devices (Linksys WRT54GL or NSLU2, for example). They're cheaper and probably use even less power than an Epia, and can manage many low processing always-on tasks.

Re:

[MikShapi]

>>Use two PCs. One small Via Epia 700mhz to do your webserver and bit torrent, and another PC with whatever spec you desire to use when you need to do processor-intensive stuff.

Almost.

For fileserver/bittorrent client, use a NEW via C7 that has ONBOARD GbE and is FANLESS. The J7F4 has two GbE, is fanless, (relatively) fast and ultracheap. The EPIA EN12000 or EX10000 or Jetway J7F2+daughterboard are also good, but are more expensive. The former is CHEAP, and you can use the PCI slot for a 4-port SATA ca

Low power consumption CPU is needed

[ipsender]

Simple... run Linux on an ARM-based machine - http://www.iyonix.com/ [iyonix.com]

Re:

[aliquis]

For that price he could probably afford loads of electricity.

Two words. PSU & powernowd

[A beautiful mind]

1. Buy a good PSU, one that is energy efficient.
2. Run powernowd (with AMD cpus, under linux), which scales down your cpu clock if not under heavy load.

powernowd obsolete - use cpufreq ondemand

[Splork]

powernowd and any other userspace cpu freq+voltage managing daemon are long since obsolete.

modprobe cpufreq_ondemand
/usr/bin/cpufreq-selector -g ondemand

now tune the up and down thresholds to your liking in the /sys/devices/system/cpu/cpu0/cpufreq/ondemand/* "files" and you're good to go.

Also, for Athlon64 and Opteron CPUs you really should enable clock divide in halt to save even more. For instructions on that read opteron-powersave.txt [electricrain.com]. (some BIOSes enable it by default, others do not)

Another mislead AMD/Intel power comparison.

[John Jamieson]

Sorry dude, Core 2s do NOT have significantly lower power consumption than AMD processors.
And even when they do, it is not so spectacular when you factor in the lack of a memory controller. (I like the Core 2, hate the P4)

Sorry, this is a COMPLEX subject. How so? Intel and AMD measure Power needs by a different yardstick. AMD makes many parts, has two different processes, and even on the same process has varying power needs.
The AMD 65nm desktop chips use VERY LITTLE power, often kicking the butt of the core 2 duo, especially at idle.

If you really want to save power on a powerfull x86, you undervolt/underclock a 3600x2 65nm chip. At this point, you will worry much more about the power consumption of your Power Supply, Video Chipset and Hard Drive.
As some have suggested, Plug in a large Flash memory device for files accessed but not updated regularly, spin down the HD after a time delay(HD's have a finite number of start ups), look for an efficient supply, and look at the newer AMD integrated video chipsets.(I think you will find these chips consume much less current than others)

Re:

[dnorf87]

AMD and Intel rate their processors TDP (Thermal Design Power) differently. Intel rates their TDP by typical usage, while AMD gives the maximum the chip is capable of consuming under severe conditions. Check out the TDP of comparable Intel and AMD processors, then get back to me on that. I think AMD's power consumption is pretty impressive if you include the fact that they have an integrated memory controller, and how they are usually a process behind Intel (90nm AMD vs. 65nm Intel). At least AMD has new, v

Re:

[bcrowell]

and look at the newer AMD integrated video chipsets.(I think you will find these chips consume much less current than others)
I just built myself new AMD64 system yesterday, and installed ubuntu on it. It is indeed very power efficient. I'm using one of the AMD64 dual-core chips that only draws 65 W peak power. When the processors are idle, and the screen is powered down, it only draws 31 W for the whole computer! That's not in sleep mode, that's just sitting there in the GNOME desktop with the screen powe

Re:

[aliquis]

Uhm, I've got the impression that AMDs is quite basic and works best when the CPU is more or less idle, but when it does it clocks down further below than the Intel chip (atleast back then) and that it's therefor more efficent for a system which is mostly idle. The Intel version however is more advanced and also works to some extent during load and therefor the Intel chip will use less electricity on a more busy machine.

Is that still true? Have it ever been? :)

Regarding power consumtion then no, the Intel c

Don't forget the monitor

[Pyrex5000]

Using an LCD monitor instead of a CRT will drastically cut your power usage. Turning off the monitor while not at your computer will help as well, instead of just letting the screensaver run. The monitor can consume more power than the PC itself.

Re:

[shaitand]

This is my typical recommendation for clients. Power management functions in windows are highly unstable. The PC doesn't wake half the time if you use any power management beyond having the monitor go on low power mode. The monitor uses less power when off then on low power mode.

The advice is simple. Turn off all power management. If you walk away for a second your system will be ready and responsive. If you walk away for 15+min turn off your monitor. If you leave for 8hr+ turn off your PC.

Re:

[John Jamieson]

I agree, screensavers are a power robber. Not only does the cpu/gpu work harder(thus consume current), the monitors are active as well.

On the other hand, I want to caution that in Monitors or TV's, LCD's do not always save much power per inch of display. It depends on the model. I have one CRT that takes only 30 percent of the standby power of one of my LCD's. Since they are "off" more than on, this negates a lot savings.

An interesting side note, my CRT takes less power when displaying a primarily black

Re:

[amorsen]

An interesting side note, my CRT takes less power when displaying a primarily black screen, my LCD's don't.

That is expected, actually. LCD's work by blocking out the backlight. Their "natural" state is transparent, so in theory they should even use slightly more power when showing black. In practice I doubt you can measure the difference.

Re:

[Seumas]

I have found that the best way to conserve power and reduce your electricity bill is to buy a PS3 and then let that stupid folding@home app run full time so you can do a bunch of work for some corporations via Stanford and pay for the electricity it consumes as well. Nothing says cost savings like running a power-hungry heater like the PS3 full time! And even better, make sure to keep your television on so you can watch the fancy folding screen saver!

Re:

[compwizrd]

I just swapped out a 22" CRT to a 24" LCD panel, and my usage at the wall went from 210W to 150W

Re:

[pla]

I just swapped out a 22" CRT to a 24" LCD panel, and my usage at the wall went from 210W to 150W

Yeah, sure, brag about it. ;-)

Not sure how you got 150W, though... All common 24" LCDs have a rated max in the 95-105W range, and at least from my experience with smaller LCDs, they usually use between half and two-thirds of that rating under real-world conditions. Granted, you'll have some losses at the power supply (if it has an external brick, I don't think they need to include that in the rated consumpt

Re:

[compwizrd]

Oops, that 150W includes the P4 2.4ghz w/2 HD's and a gig ram of ram that is attached to the UPS as well.

Kuro Box

[Anonymous Coward]

I just recently bought a Kuro Box for exactly the same reasons - low power, low noise, always on. You can load it up with Gentoo or Debian, so you can do bittorrent, ftp, http, etc. And it's cheap!

The only downside is that it's headless, but for me that wasn't an issue. If that really bugs you, you can set up a vnc server on it and graphically steer it from your PC.

Check out the kuro website. [kurobox.com] It has links to their wiki and forum.

Re:

[harryman100]

This works well as a server, My flatmate recently bought one, and it worked pretty nicely out of the box - he stuck gentoo on it (which took a bit of fiddling), but now has a v low power file/web/subversion server which is on constantly.

However, the power is LOW, don't expect to be able to do much other than just let it sit and serve a few bits and pieces. I bought myself a Via Epia fanless 1GHz motherboard last october, which works as a mythtv front/backend, apache server, subversion server, a synchronisat

Re:

[aliquis]

Maybe we should mention Genesis Efika [pegasosppc.com] aswell, cheap mobo + 400MHz PPC + 128MB ram + 100mbps.

VIA boards work well, but not as fast as Core

[wirelessbuzzers]

For off-the-shelf desktop use, it's hard to beat the Mac Mini. Core duo, notebook hard drive, notebook optical drive, draws like 50 watts at idle. I hear the Acer L320 is going to be similar. No graphics in the Mini, but maybe there will be in the Acer. Good graphics cards are pretty much guaranteed to have high power consumption these days; I'm not sure if you can idle them down.

For light-duty serving, I've been very happy with the latest round of VIA boards (and I've heard the slightly cheaper Jetway variants work just as well). I have an EPIA EN12000EG fanless board running in one of those $30 mini-tower cases from Fry's (or something). The board draws something like 13 watts at idle, and 25 under load. This includes the CPU, RAM and chipset. If you can spin down the hard drives, they'll only be a few watts more, and adding in the PSU inefficiency, it'll be maybe 40 watts AC.

If you just want to serve stuff, you can toss in a 2.5" SATA hard drive (or two, for RAID) and no optical, and fit the whole thing into a case smaller than a Mac Mini, for a lower price than the Mini, with less power consumption than a Mini, even with 2x160GB notebook drives. Or you can put in an optical drive, and it'll be slightly bigger than the Mini.

I've used one of the previous round of these as a desktop machine. Its audio is decent, and as long as you're mostly browsing the CPU is fast enough (compile jobs are slow, but they're much more tolerable with the new C7 proc). The integrated graphics suck, so you won't be gaming on it.

Re:

[MojoStan]

For off-the-shelf desktop use, it's hard to beat the Mac Mini. Core duo, notebook hard drive, notebook optical drive, draws like 50 watts at idle.

Since the anonymous reader wants to "build" the PC, I think a Mac mini recommendation (a good pre-built choice) should be accompanied by the AOpen miniPC barebones series [aopen.com]. The specs and form factor are nearly the same, but AOpen allows a wider selection of components. Systems can be assembled-to-order at MyAOpen.com [myaopen.com]. Barebones miniPCs can be bought at many places like Buy.com and TheNerds.net.

If this form factor is restrictive, then the Mac mini's energy efficient notebook chipset (Intel 945GM) can be ha

Re:

[jabuzz]

While a Mac mini is power efficient, the point is that something like a Via C7 mini-ITX is more power efficient still. I recently built an always on device, used a EPIA EN12000G fanless motherboard, with a picoPSU 60W power supply, 512MB of RAM, a 60GB 7200RPM always on rated Hitachi 2.5" drive (you can get up to 160GB 7200RPM laptop drives now), and fitted it in a Pack-BOX enclosure, complete with a PCI Unicorn based ADSL card. They do a slightly bigger version of the case that takes a 3.5" drive or two 2.

A laptop

[pipatron]

A laptop is already constructed to use as little power as possible, so for non-performance critical tasks, it would probably be quite useful for an always-on server. Built-in UPS is also handy, and it can be tucked away in some closet without taking any room, while still having an emergency keyboard and screen if you need to perform administration tasks on it.

For storage, a couple of USB-drives would be useful, I bet they don't draw much more power than the drive itself.

Re:

[bendodge]

Yeah, I bet a drive doesn't draw much more power than the drive itself.

Re:

[Atlantis-Rising]

But the enclosure does.

USB drives a very bad choice for power savings

[jbridges]

Bad idea to use USB drives for low power because they generally do not spin down when idle.

Same is true with most RAID adapters (Areca does support spin down).

Re:

[Overzeetop]

How much storage do you need? Spindle running, no read/write values are in the 2-5W range, with peak write at about 12W. A small laptop will happily chug at less than 40 watts, and 750GB drives are available with 1TB in oem hands right now. I daresay under 50W at idle (prob 40W w/ the screen off) is going to kick the butt of most desktops without a monitor.

While it would be nice to save those three idle watts, I think the cost of a full system would probably outweigh that loss.

If using AMD Athlon 64...

[antdude]

... use its Cool'n'Quiet if your motherboard has this CPU and supports it. It's nice when idled and not using the machine so much (e.g., surfing the Web).

Now, if I could make my Windows XP Pro. SP2 stable. Others and I [amd.com] can't figure out why I get blue screens with Cool'n'Quiet enabled.

Underclocking

[pizza_milkshake]

Check out your underclocking options on your current machine; I found that Linux's 'ondemand' cpufreq policy governor made a real difference on my machine: http://parseerror.com/~pizza/cpufreq.html [parseerror.com] You can also check around in your BIOS to underclock your machine; but the disadvantage there is that the change is permanent; with Linux's CPU governors and a modern CPU your machine runs at full clockspeed only when the cycles are needed; I believe Windows has similar options.

Re:

[antdude]

I am doing the same with my AMD Athlon 64 754 system. It seems to work well. See my newsgroup thread [google.com]. I tried stressing it and idled it.

Temperatures are nice when idled (room is about 78 degrees(F):
temp1: +95 F (high = +172 F, hyst = +106 F) sensor = thermistor
temp2: +96.8 F (high = +176 F, hyst = +167 F) sensor = thermistor

A used Pentium-M based laptop

[Jerf]

Buy yourself a used Pentium-M based laptop. If you don't need to actually use the computer directly, buy one with the screen broken, which tends to make for some darned cheap laptops. You can hook up a monitor to it, which is how you'll put your OS on it. (Remember, laptops have mouse ports, USB ports, and display, so you can use them as a conventional computer just fine, and most laptops have the graphics chips to drive a higher resolution that their native LCD resolution.) The money you save on buying a cheap laptop like that make up for a lot of power bill, especially with the broken screen bonus.

Get the model number of the laptop in advance, cross-reference that with the chip that it uses, then find the power consumption for that chip if you want to double check. I hear the later-model ones are (surprise surprise) more efficient, but they're all pretty good AFAIK.

As somebody else said, the built-in UPC isn't bad, and a Pentium M will have all the power you need for non-floating-point functions; any Pentium M can handle even a moderately-sized website if you wanted.

PC vs Mac electricity consumption

[lancejjj]

My home PC server, which I left on 24x365 for email, backup, etc, ended up costing me well over $150 per year in electricity just for the PC (no periferals, monitor, or anything else).

Noticing this cost, I compared a bunch of Macintosh and PCs, as you can see in this article on PC and Mac electricity use. [blogspot.com]

As you can see, it's pretty easy to see that the cheapest devices can end up costing more in power alone.

If you plan to run an electronic device close to 24x365, factor electricity consumption into your purchase decision. Also factor in devices like cable modems, wireless routers, and so-called "sleeping equipment" - in combination, they can easily put another several hundred to your electricity bill every year. I use an X10 "appliance" controller to truly switch off idle equipment.

My total monthly electric consumption these days is well under 100 KWh.

Re:

[Urgoll]

My total monthly electric consumption these days is well under 100 KWh.

My god, what kind of house do you have to use that much electricity, and where do you live? My house doesn't use a quarter of that in a full year, including heating. And I'm in Canada!

Re:

[Nonac]

I suspect you are misreading your electric bill. Even turning on a 25 watt light for three hours every day would use more electricity than you are reporting. The average US household uses about 9000kwh per year, so the 100kwh per month stated above actually is pretty low.

Re:

[lancejjj]

My god, what kind of house do you have to use that much electricity, and where do you live? My house doesn't use a quarter of that [100 KWH/month] in a full year, including heating. And I'm in Canada!

A single 100 watt incandescent light bulb, on 24 hours a day, consumes roughly 73 KWH per month:

100 watts * 730 hours/month = 73,000 watt-hours per month, or 73 Kilowatt hours per month.

Your 25 KWH over a year is equal to having a 3 watt light bulb on 24x365. Either you freeze your ass up there, or you might calculate KWH differently in Canada.

Re:

[aliquis]

Uhm, you are thinking about 100.000 kwh, right? :)

Re:

[Overzeetop]

That's pretty impressive. Around me, that would mean an electric bill of about $18/mo, $10 of which would be taxes and billing fees.

A laptop with no fan...

[neurocutie]

As several have mentioned, the obvious choice for an always-on PC is a laptop, as long as you don't require a lot of disk bandwidth. Remember that even an old 486-66 can saturate a T1 line, so almost any laptop will do (but get one with a good lithium battery, definitely not NiMH or NiCd).

The added advantage of these older laptops is that their CPUs do not require a fan -- the fan is the number one problem with most PCs. I've had PC's run for *years* continuously without reboots or crashes. Invariably what

Get a vhost

[Mr.Ned]

A good option is to get a cheap virtual host. You get root, install what you like, run what you like, and it uses less power - none of yours - because there are several mostly-idle virtual machines on the same host.

Disk space is relatively expensive, and this may not be an option for you if by 'BitTorrent' you mean 'fill up my 500GB hard drive'.

ideas

[bcrowell]

As others have pointed out, if you can find an obsolete laptop, and just dedicate it for your 24/7 applications, that's going to be by far the most energy-efficient solution.

Get a Kill-A-Watt [thinkgeek.com], so you can actually measure how much power various things are using. Until I got one, I had no idea that my computer's speakers were drawing 12 W all the time, even when the computer was shut down.

2.5" hard drives are more energy efficient than 3.5" ones. You need an adapter cable, and also an adapter to mount it in a standard desktop PC's cage. A 2.5" drive is more money for the same storage, but all hard disks are ridiculously huge for most people's needs these days.

Get an 80PLUS rated power supply. The 80PLUS thing means that not only is it efficient, but it's also made in a more ecologically friendly way, without lead, etc. I've heard a lot of conflicting claims about how you should choose the capacity of your PS compared to the power your machine uses. Some people say a switching PS is most efficient if you run it near its maximum capacity, and others say it's most efficient at 50%. I came across something on usenet recently where they actually collected data, and they found there really wasn't any clear relationship. It's dangerous to get a PS that's not rated high enough, because your machine may use an unusually large amount of power during the boot process, and it may boot unreliably if your PS isn't rated high enough.

Try to get all the ACPI power management features of your machine working. Unfortunately, that can be easier said than done. Many BIOSes default to only doing S1 sleep mode, which hardly saves you any power at all. That's because a lot of older hardware can't handle S3.

For your mobo, choose something with integrated video, rather than using a video card. If you're into gaming, this is yet another good reason why you don't want your always-on machine to be the same as your main machine you use all the time.

Re:

[evilviper]

As others have pointed out, if you can find an obsolete laptop, and just dedicate it for your 24/7 applications, that's going to be by far the most energy-efficient solution.

That's an easy way to get energy efficiency, but you can build a desktop more efficiently. 80PLUS PSU, Turion CPU, etc., and your desktop can be lower power than older notebooks, while significantly faster.

Some people say a switching PS is most efficient if you run it near its maximum capacity, and others say it's most efficient at 50%

Re:

[rossifer]

That's an easy way to get energy efficiency, but you can build a desktop more efficiently. 80PLUS PSU, Turion CPU, etc., and your desktop can be lower power than older notebooks, while significantly faster.

How old of a laptop are you talking about? My svn/trac/ftp/web/email server is a 2001 IBM Thinkpad A21p (850MHz P-M, 512MB RAM, 100GB 7200rpm drive) that draws 20W idling and 34W going full tilt (with the screen off, natch). According to the numbers on the power brick, my 1999 Thinkpad 600X had similar

Re:

[evilviper]

There's no good to mediocre desktop PC (aside from the Mac mini, which is essentially a laptop in a different box) that consumes that little power with any kind of performance.

I said, in no uncertain terms, "you can build a desktop more efficiently."

So, what kind of power consumption can you get from a desktop?

Slightly lower than you can from even the best laptops. Mobile components work just as well in desktops as they do in laptops (eg Turion CPU). However, you can get slightly higher efficiency from th

Re:

[rossifer]

I said, in no uncertain terms, "you can build a desktop more efficiently."

I'm also talking about building a low-power computer, and in my experience, I haven't been able to get close to laptop power usage, let alone better than laptop power usage.

Slightly lower than you can from even the best laptops. Mobile components work just as well in desktops as they do in laptops (eg Turion CPU). However, you can get slightly higher efficiency from the power conversion, slightly more efficient components like video.

Re:

[evilviper]

This machine idles at 75W and uses 140W when playing a DVD in MythTV.

Those are INSANE numbers.

Antec NSK2400 case (380W power supply with 85% tested efficiency), ECS Micro ATX motherboard, 2.0GHz Turion CPU, 2GB DDR RAM, 80GB 2.5" SATA HD, NVidia 7600 fanless video card.

A 7600 GT (you didn't specify) would almost entirely explain the power consumption.

There's a 10W difference between a MT and ML Turions.

Your PSU isn't 80plus certified, and isn't quite as efficient as you think: http://www.silentpcreview.com [silentpcreview.com]

Re:

[rossifer]

You've inspired me to do some more research into the possibilities of a low-power desktop. After all of this research? A 2-3 year old used laptop with the screen powered down (or a 1-2 year old Mac mini) seems to be the best bet for a low-power 24/7 server that doesn't break the bank on initial cost or power bills over time.

Slightly lower than you can from even the best laptops.

This [silentpcreview.com] is an article by Silent PC Review on a "Mobile on the Desktop" build up, and the best they were able to do was 22W/57W. Th

Re:

[evilviper]

"Find an obsolete laptop" means buy a used one, not build one from scratch.

"That's an easy way" means: that's an easy way to do okay.

You simply cannot build a desktop machine that's lower power than any reasonably modern notebook. See this post, for example.

That's idiotic. Just because a few people don't know how to do it, doesn't change the facts.

Be careful with VIA EPIA stuff

[DaleGlass]

I tried to use that as a base for a silent box some years ago. This didn't go well.

I got the "Nehemiah" version, which uses a 60mm fan. I also got a case with a fanless supply (brick + electronics in case) to try to make it as silent as possible.

• 60mm fans are noisy and hard to silence. The case was too thin and cramped to install anything larger in it and had two 60mm fans as well.
• The board itself was crap. Performance was very unimpressive (but that could be expected). It turned out my board had only the R

Re:

[dbIII]

I've had the opposite experience with similar gear. The differences were a slower CPU than the "Nehemiah" so completely fanless, and it isn't a VIA motherboard even if it uses their chipset (ebox-III - I got the "big" one with enough space for a laptop disk and a parallel port - but still smaller than a mini-ITX system). Having a solid aluminium case that looks like a BBQ plate and a big heatsink that is stuck with thermal paste to the case helps. I also put Gentoo on it so I could squeeze as much out of

My Strategies

[the eric conspiracy]

Turn the monitor off when you aren't using it. An LCD monitor is more energy efficient than a CRT.
Buy a low-end video card. The high end cards are energy hogs.
Use a CPU that you can scale back operating frequency on using CPUSPEED etc when the machine is idle.
Don't buy more CPU speed than you need. Consider buying a low power version of the CPU you are getting.
  Consider a motherboard that you can use a portable CPU on.
Buy the smallest feature size CPUs. They are usually more energy efficient.
Use smartd etc. to spin down your hard drives. Right now that usually means IDE drives - spinning down
    SATA drives on Linux can be a challenge - it depends on kernel & drivers. Each hard drive = 10 watss
Don't install more RAM than you need.
Get a motherboard that allows you to turn off unneeded stuff like serial ports etc.
Buy an efficient power supply.
Use something like the Killawatt power meter to measure your results.
Switch to compact flourescent bulbs!!

Do all this and you should be able to get into the 60-70W idle range. Since 1W-year
=$1 that is $60/year.
The flourescents will save you at least another $100/year.

Re:

[scdeimos]

And don't use anything other than a "Blank" screen saver, reducing CPU/GPU loading when the computer is just sitting idle.

Re:

[compro01]

another thing is underclock the CPU.

Re:

[homer_ca]

Undervolting goes well with underclocking too. If you have a good CPU, you can undervolt a lot even at stock speed. You can tweak it pretty easily in Windows using RMClock. It's a little more challenging in Linux, but still possible. You have to edit the voltage tables in the speedstep_centrino kernel module and recompile it.

http://forums.gentoo.org/viewtopic-t-341298-highli ght-undervolt+speedstep.html [gentoo.org]

My build

[TopSpin]

Optimizing for low noise and cost based on off-the-shelf parts led me to this setup. It isn't the lowest power setup I can imagine, but noise and power are directly proportional in most cases. My goal was a very low noise, low cost always-on headless server running Linux with fault tolerant storage, at least one Gb NIC and enough processor and RAM to use for common development tasks. Based on measurements performed here [silentpcreview.com] and some guess work I estimate this is pulling 40W at idle and I can't hear it a beyond a meter.

MB: ASUS M2NPV-VM. AM2 socket with on-board Nvidia video, SATA etc. Not running a discrete video card is a large power savings.

CPU: Athlon 64 3500+ AM2 Lima core. This is a recent single core CPU from AMD. Easily obtainable from Newegg et al. The nice thing about it is the low TDP of 45W. This approaches portable CPUs while not costing so much. Stable at 1.2V (perhaps lower if I tried) and works well with cpufreq.

Case: Antec NSK3300 MicroATX. Small and quiet. Uses a high efficiency 300W power supply with a non-standard form factor. I doubt this machine can pull enough juice to get the fan moving at full rate. It's silent 99% of the time.

The rest: 1GB of "value ram", a pair of quiet 250GB WD disks and a Intel Gb PCI NIC I got somewhere. If you want to save more power run 1 disk, cut the RAM in half and don't add a fast NIC. Probably just under 30W at that point.

Re:

[afidel]

Why not go with the 64 x2 3800+ EESFF which has more horsepower and a TDP of only 35W. Also using less ram might result in MORE power usage as the HDD seeking probably uses more power than the RAS cycles on the ram.

Two boxes is the way to go

[toddestan]

It sounds like you leave your computer on all the time, and use it for a variety of tasks, and you are looking for a machine that can do all of that while being easy on the electric bill. This hard to do, as things like high powered CPU's, high end video cards, and lots of storage tend to not be low power. I suggest you get two computers. Get a low power machine, either an old laptop or a P3 and offload all the tasks like the FTP server and the bittorrent duties to this machine, and leave it on 24/7. Old laptops work great for this, as they are built for low power and have a built in UPS. P3 systems also work well, many ex-corporate P3 class systems are quiet, low power, easy to work on, and dirt cheap. Then you get a high power machine, and only have it powered up when you need it. You can have the two computers set up next to each other, and use Synergy [sourceforge.net] to run your IM/IRC on the 24/7 computer while doing whatever on the high end machine at the same time.

If you still must have it all in one desktop machine, one way to cut the power usage if you like lots of storage is to try to only have 1 HDD in the computer, and put the rest on USB/Firewire harddrives which you can then shut off when you don't need them.

Hackable linux router

[Chris Pimlott]

Depending on what you want to do, you may be able to get away with using a linux-based router running OpenWRT (or something similar) for some services. You won't be able to have any large local storage (although you can access other drives over the local network), but the power usage would be pretty hard to beat.

Re:

[John Jamieson]

Good point. Another option is the Linksys NLSU2 or the newer Gigabit Buffalo storage device. Do some homework to figure out how you are going to spin down the hard drives ahead of time. (do you want to buy a drive that supports it, or do it in software)

Some ideas of my own

[Ant P.]

I've tried to solve exactly this problem myself. Here's a few things I've tried:

• Strip down the hardware. Having another PC is a good place to start, that way you can run a headless server. Disable things you don't need in the BIOS. If your stuff isn't CPU-heavy, consider using a Pentium 2. They can run fanless, which is a nice thing to have in any case. If you can live without optical/floppy drives, disconnect those too.
• Tweak the kernel. cpufreq is quite good, works on a lot of processors and doesn't have much of a performance impact. Remove or modularise any hardware drivers you don't need, since the kernel might decide to keep them powered off if it can't use them. Also enable performance tweaks like DMA in the disk/network stuff.
• Don't run unnecessary software. More unused RAM is more disk cache. Read the documentation on Linux's laptop mode setting too - you can make it force the hard disk to stay powered down and only write every few minutes. If you can, just skip the hard disk altogether and run everything from tmpfs.

If you're still not satisfied, you could try some more extreme methods like disconnecting indicator LEDs.

Bios

[chriso11]

I'd like to echo some of the above points. I was making a NAS server that was to be on 24-7.

1) Dump the high performance GPU. A cheap PCI video card saved me 50W.
2) Seasonic makes some nice 80% efficiency PSUs. Well worth it.
3) Turn off integrated peripherals in the BIOS. Are you using the Parallel ports and serial ports? Lower the bus frequency if you can.

I found that a cron job to turn off the CPU at midnight, along with the auto-turn on timer in the BIOS set to 7:00 also worked quite nicely.

Re:24 X 7 NAS

[Technician]

I was making a NAS server that was to be on 24-7.

I considered making a NAS, but it was about the time several NAS in a box solutions came out. Lacking space for yet another full size box and concerned about I went with one of the pre-packaged solutions. I settled on one that does run Linux. It uses a Riser filesystem. It supports both the Unix shares as well as SMB, both of which can be shut off. The drive is easly partitioned for mounting an encrypted partition. This works well. A mounted encrypted p

Silentpcreview.com

[sgent]

Take a look at Silent PC Review [silentpcreview.com]. Although concentrated on silent computing, any power usage produces heat requiring fans -- so they spend a lot of time worried about power/heat as well. The site is focused on building your own pc, so they do a good job reviewing components, 2.5 in disk drives, etc.

One word: laptop

[Cervantes]

One word: laptop.

I picked up an old Dell 1Ghz laptop, added an external HD with a USB enclosure, and plugged in all my gizmos with a docking station. Now it does all my 24/7 tasks, hosts my domain, etc. A PCMCIA -> SCSI card serves up my tape backup. VNC means I can keep it tucked away in my rack (though, technically, it's connected to my KVM too), it's quiet, power efficient, low heat, and a little research ensures it won't explode on me.

Don't get me wrong, it's no speed demon, things run slower than if

Not a good laptop application

[Whuffo]

I tried doing this with a laptop. I found that a moderately loaded laptop running 24/7 generates a bit more heat than it can dissipate; it was OK all winter but when the house warmed up in the summer it started having problems. It died while I was trying to figure out what to replace it with; the main board was turning brown from the long heat soak. The answer was a small Pentium-M based desktop machine. With a right-sized power supply, large fans turning very slowly, etc. it's very quiet and uses very lit

Think different... use an NSLU2

[mspohr]

In looking through the reasons you need to have an always-on PC (web or FTP servers, BitTorrent, or simply to make sure I don't miss any messages on IRC or my instant messaging client), it looks like most of these could be done using a Linksys NSLU2 with Linux installed. You will need to fire up another PC to access it but I hope you won't be sitting in front of the PC 24/7.

It uses only about 5w and you can attach flash or USB disks if you need more memory.

http://www.nslu2-linux.org/ [nslu2-linux.org] will tell you everything you need to know to set up the applications you need.

Forget VIA, get an underclocked Sempron

[AmiMoJo]

Get a Sempron and underclock it. Check out the Silent PC Review forums for info on good boards and sockets, but IIRC the 3200+ 939 is a good underclocker. Run at low speed and voltage with a high efficiency PSU.

The VIA EPIA boards are all very nice, but when you look at the cost of the board, enclosure, psu etc, you realise it will take about five years to recoup the cost in saved electricity vs the Sempron.

That is the biggest problem with energy efficient tech IMHO - it's too expensive. 25 years to recoup my £10,000 investment in solar panels? No thanks.

Linksys slug - or other options

[itsdapead]

I use a "hacked" Linksys NSLU2 [nslu2-linux.org] to run:

1. Network-attached storage for back-up/file sharing (its intended purpose) (samba)
2. DHCP/DNS service for my local network (dnsmasq)
3. IMAP mailbox/mail gateway (CYRUS/Fetchmail/postfix)
4. local iTunes server (mt-daapd)
5. VPN access to home from work/mobile - "properly" through openvpn, or using ssh port forwarding (often easier).
6. Long downloads with ctorrent, wget etc.

I'm using it with an external USB hard-drive, but its quite possible to use a USB key (in which case it woul

Laptop

[fozzmeister]

Is probably the most mature low power solution, other alternatives are things like MicroATX etc.

Turion-based PC

[MobyDisk]

Here is my article on my low-power, quiet HTPC. [mobydisk.com] I used an AMD Turion, but a Pentium-M works just as well. My goal was to make a PC that would not overheat even when it was enclosed in my home theater with my DVD player, PS2, etc.

The other option is a Mac Mini, Apple TV, or a laptop.

Re:

[jdray]

An article over at macnn.com about how a Mac Mini outperformed an (old) XServe [macnn.com] says that the Mini used .37 amps at its peak. Presuming that was measuring the 110 Volt side, that's just over 40 Watts running full steam. I'd call that fairly power efficient.

Re:

[zerOnIne]

Beware of that plan! I tried that exact same thing this past December and quickly found out a very odd "feature" of most CF-to-IDE adapters; specifically, they don't wire through DMA properly. So your BIOS will support DMA, your CF card will support DMA, but the signals never actually get through. Now it takes this particular machine a few minutes to boot while linux tries to turn DMA on but keeps timing out. And yes, I've tried passing a few different kernel parameters at boot time but to no avail. You'r

USB-to-CF Adapters

[billstewart]

You can also get USB-to-CF adapters, and assuming they're USB 2.0, they should do about as well as USB memory sticks for performance, while letting you use that old CF if that's useful to you, or new CF if you prefer to buy your memory that way.

And assuming that your OS will let you spin down the disks that aren't in use, keeping most of your running system on CF will keep things quite and low-powered except when you actually need disk.

Re:

[zerOnIne]

Yeah, I picked up a no-name adapter, and poking around online afterward this seems to be a fairly common problem. It's apparently something that's not hard to get right, but just a lot easier to get wrong.

Re:

[saskboy]

You could also run the OS right from RAM, if you use a small distro like Damnsmalllinux.org and avoid using a hard drive completely. The storage can be on a USB memory stick.

Re:

[Iron Condor]

I had been looking into that but decided against it since I'd need a HDD anyways for all the services the OP talks about - from receiving messages, through web-serving through torrenting - you name it. By the time you're actually using your server, there's always some kind of activity that wants the hard disks spun up at least once every 20 minutes or so - so if it is effectively always spinning, then I might as well pot /boot onto it as well and skip the whole memory-stick thing entirely.

However I really

Re:

[gigne]

Even better get a Gumstix and the addon Etherstix. You can then connect it to your NAS server over ethernet. I run a similar arrangement myself, and in general I find the Gumstix too slow to handle heavy torrents.

Re:

[Ihlosi]

Seriously go with the new core 2 duo. It uses way less power than it's predicessor the P4.

Even better - go with an Athlon 64. In most usage scenarios (i.e. the CPU is idle most of the time) it uses even less power than the Core 2 Duo.

If you plan to run the thing at close to 100% CPU load all the time, then the Core 2 Duo is more efficient. But that's a fairly rare scenario.