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?"

Comments

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 power. So, don't buy an expensive new PC claiming you are saving the planet.
I have such a box myself, it runs MythTV, mldoneky, a webserver, dhcp, samba, mail server... I made it 4 years ago using a cheap 2.4GHz Celeron which is dog slow yet is more than enough for the tasks. On a supply meter it uses an average of 60W. This translates to about £60 of electricity a year ($120).
Say I make a new machine which uses just 40W (unlikely), this machine would have to cost less than £20 per year of usage. In your 3 year cycle you would have to make it for £60 ($120).

Re:Dont bother.

[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:Dont bother.

[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.

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.

[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 wake the desktop, then the desktop can turn on its own speakers and wake me!

Low power consumption CPU is needed

[ipsender]

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

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.

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.

Gumstix

[Anonymous Coward]

Use one of these: http://www.gumstix.com/

Re:VIA boards work well, but not as fast as Core

[Anonymous Coward]

It should be pointed out that the Mac Mini is efficient for the fact that it primarily uses mobile components -- things that normally go into a laptop. I think the power consumption numbers the parent quoted would also include the display, as I believe the Mini only consumes around 20W at idle and 25-30W under load (say... playing a DVD).

With that being said, laptops are also a good option and are typically more efficient, consuming 30W under load, and that includes a display which can always deactivate itself after a certain amount of idle time. Mobile power management is also typically as good as you get. A Core2 Duo is also overkill for things like HTTP and FTP servers -- I used to do virtual hosting for friends way back on a Pentium 200 w/ 200MB of memory without a problem. You get the option of mobility to boot, even if it largely stays parked on your desk.

Storage is always limited, but external firewire drives can add a lot of space without a lot of noise, and with excellent performance. I have a 500GB WD myBook. It spins itself down after 10 or so minutes of inactivity, and when spun up it's barely audible.

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 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:My build

[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.

Re:Kuro Box

[Anonymous Coward]

There's something similar from linutop.

I'm a little nervous about running a diskless system with only 128 or 256MB though. To do without a swapfile, I'd want more RAM than that.

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:Two boxes is the way to go

[Verte]

I concur- one more powerful computer you can use for your real tasks, and one for your background stuff. these guys have some interesting stuff. There was one company in a post on /. a while back that had a 1GHz ARM machine in a really, really tiny case. Can't seem to find the article.

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 little power. This little machine (2 GHz Pentium-M) is running my home controls and weather station, doing frequent FTP uploads of weather data, serving web pages, acting as a home file server, etc. Even running Windows XP (yes, I know) it's rock solid. After almost two years it's never crashed and only gets rebooted when the power fails or an automatic update forces it to reboot. The slow turning fans don't suck in dust bunnies, so it's been totally trouble free. You could do worse...

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.